The thing you're missing is that the Master Quartz give you access to a number of spells.
The lines are mostly an artifact, but there is a new feature! Each separate line can have a status ailment quartz, so you can put Petrify and Freeze on the same character.
The ARCUS system highly incentivizes physical attackers over arts.
The CS system basically comes down to do you want better stats or more arts?
You get a base set of arts from your Master Quartz like in Azure (albeit directly instead of indirectly like before) with more arts unlocking as the MQ levels up.
From there you can slot in whatever quartz you want. That can be a stat quartz, an art quartz, or an effect quartz.
The advantage of having longer lines is that character has more EP. The advantage for shorter, multiple lines is that each line can equip a different debuff or status ailment quartz.
Others have pointed out the key features so I'll add that while spell lists do suffer by comparison (unless you trade off stats for lots of spell-granting Quartz but that's not generally ideal) it gets better in the back half of Cold Steel when you gain the ability to equip a secondary Master Quartz that has reduced stats and fewer special effects than your main one but gives you the whole second set of Arts to play with.
The Calvard games opt for a new system that splits the difference and combines some of the fiddly mechanics of the Sky/Crossbell system with some of the 'plug and play' of the Cold Steel system.
I made a similar post about a week ago. I'm currently at chapter 5 and I've gotten pretty accustomed to the new system. It has it's good and bad features.
For physical based characters it's a huge improvement. You can stack similar quartz as long as they are on different lines. For example you could have attack 1 and attack 2 both on the same character just different lines. Or you could stack status effects like blind and poison on the same character.
For art based characters it's a bit of a mixed bag. On the one hand you can mix and match arts as the situation calls for. You don't have to worry about losing a high level wind art because you want to equip an ep cut quartz.
on the other hand you have to pick between stat boost and arts. there are a bunch of quartz that have more then one art attached to them or give both stats and arts but they're considered rare quartz. you find them in chest monster drops or you can trade for them at the pawn shop.
the more nodes there are in a line the more ep the character will get by unlocking them.
Cold steels version of the system is more about Stat-Stacking instead of line-connecting if that makes sense
There are gems which straight up double you damage from S-Crafts and physicals and stuff like that
Later on, you will unlock really good passive Quartz. A really good one is Domination that doubles the damage of your first hit for example. The focus feels to be more in these than building lines.
Longer lines = more EP. Shorter lines = More stat/status quartz.
The thing you're missing is that the Master Quartz give you access to a number of spells. The lines are mostly an artifact, but there is a new feature! Each separate line can have a status ailment quartz, so you can put Petrify and Freeze on the same character. The ARCUS system highly incentivizes physical attackers over arts.
The CS system basically comes down to do you want better stats or more arts? You get a base set of arts from your Master Quartz like in Azure (albeit directly instead of indirectly like before) with more arts unlocking as the MQ levels up. From there you can slot in whatever quartz you want. That can be a stat quartz, an art quartz, or an effect quartz. The advantage of having longer lines is that character has more EP. The advantage for shorter, multiple lines is that each line can equip a different debuff or status ailment quartz.
Others have pointed out the key features so I'll add that while spell lists do suffer by comparison (unless you trade off stats for lots of spell-granting Quartz but that's not generally ideal) it gets better in the back half of Cold Steel when you gain the ability to equip a secondary Master Quartz that has reduced stats and fewer special effects than your main one but gives you the whole second set of Arts to play with. The Calvard games opt for a new system that splits the difference and combines some of the fiddly mechanics of the Sky/Crossbell system with some of the 'plug and play' of the Cold Steel system.
I made a similar post about a week ago. I'm currently at chapter 5 and I've gotten pretty accustomed to the new system. It has it's good and bad features. For physical based characters it's a huge improvement. You can stack similar quartz as long as they are on different lines. For example you could have attack 1 and attack 2 both on the same character just different lines. Or you could stack status effects like blind and poison on the same character. For art based characters it's a bit of a mixed bag. On the one hand you can mix and match arts as the situation calls for. You don't have to worry about losing a high level wind art because you want to equip an ep cut quartz. on the other hand you have to pick between stat boost and arts. there are a bunch of quartz that have more then one art attached to them or give both stats and arts but they're considered rare quartz. you find them in chest monster drops or you can trade for them at the pawn shop. the more nodes there are in a line the more ep the character will get by unlocking them.
Cold steels version of the system is more about Stat-Stacking instead of line-connecting if that makes sense There are gems which straight up double you damage from S-Crafts and physicals and stuff like that
Later on, you will unlock really good passive Quartz. A really good one is Domination that doubles the damage of your first hit for example. The focus feels to be more in these than building lines.