To be honest, I think making this change is only going to push people away from the arcade gates (where they are most useful) and into the missions (where they matter a hell of a lot less). I mean, most missions are largely structured around very specific themes as it is. Boss missions and stratums even more so (and obviously don't have arsenal stations as it is past the first level).

At most I'd suggest leaving them completely alone in the arcade. Not that I see a whole big problem leaving them in. If you want the challenge there's nothing stopping you from not using them while leaving the option to those that do. Of course, I think the loss of challenge over time has far more to do with the monster nerfs than it has with people being able to take fully specialised sets in.

I do think people are over-selling the idea that this will boost the importance of normal weapons. It won't. 4 weapon slots already saw to that well before arsenal stations popped up. A normal sword always worked as a decent started sword as you were working up to 5 star and it still is, but it has never ever been a suitable option once you've worked enough to actually start investing in specific damage type weapons and additional slots.