have fun sorting through 30 characters to figure out which one had that pretty purple ribbon you are looking for. definitely not how i want to spend my time. the other perks are nice reasons to have them, but constantly shaking down mules is the exact opposite of why i play videogames.
For me personally it won't be an issue. I feel in storages by value to character numbers and re arrange things a couple hours before every maintenance, I'm the kind of person that sorts to OCD standards and memorization. So for someone like me it's not any issue at all. But that's just me for most people if they don't set up a sorting system for themselves they will sometimes forget who has what stored to them. Taking the time memorize and marking things that need transfered and what doesn't isn't for everyone.
Personally if people are going to go through the trouble of buying a few more characters and are limited by a tight budget for the game. Then take the time early on to decide how you will arrange storages and learning which character will carry the most of specific things. This will allow you to benefit from the perks of multiple characters and solve some storage issues.
For those not limited by budgets can just buy whatever they want.