The idea about taking the brick from tower shop is based on the fact that it's basically your only not paid way to acquire them. You can get everything else in the shop from other places. Sure, you can take the tickets & increase your own disappointment in gacha, but everything other than guaranteed SSR is a fake promise. A brick however guarantees you to get a step closer to FLBing a weapon. Even f2p guys get SSR hime weapons from time to time & there are quite a few that offer you better effects than your usual event weapon FLBs. Even one of these can give quite a boost to your grid & gathering 10k medals/tower (including the ones from ranking) isn't all that impossible. I'd say defeating tower until 12F (completing all or at least most missions) will secure you that.
That said, this concept works the most if you brick a weapon of your "main" element since bricking a weapon of your pick to MLB from LB0 takes 3 towers if you gather 10k each time. You might have a million reasons to say no to this kind of future investment & some might also be absolutely justified. It's a recommended pick, in the end, not a must.