I cast it all the time, without it taking up a spell slot... in fact, I dont think its ever cost me a spell slot to cast it...
how are you doing it, that it costs a spellslot?
The issue isn't that it costs a spell slot to cast it, the issue is that it costs a reserved spell slot to cast it. Basically, every time this is going to be cast, it means the wizard is about to unlearn a spell, learn this, then cast, then unlearn this, then relearn the original spell. It's a hassle that could just be avoided by letting us cast it without having to take up a reserved spell slot since, as a ritual, it does not use a spell slot to actually cast.