Cant agree with you Tafoid, at any point.
Your solution sounds simple, but it create dependencies to third party developers, by using their cat .ini files. This wasnt needed before, it was a option and not really necessary. In your scenario now, this would be a mandatory, which is questionable. Frontend-developers would need to wait until the catlist.ini´s are published. There where problems in the past allready, with wrong formatted mamelists, where frontends stopped updating lists in the middle of the process, resulting with a bugged list.
Also there are Frontends, that use their own database, which in your scenario would become obsolete .
I dont like the whole MAME-MESS marriage at all. The day I read about the first time, I thought this would be just a optional thing, for people who compile their own MAME version and now it just turns out to be the opposite. You now need to compile your own "old fashioned" MAME, whis is a pity, sorry to say this. I dont see MESS in a state, where this whole process is reasonable.
I really dont want to bitch around here, but I would really appreciate it, if the MAME devs would reconsider their decision and if it is not better to keep this whole thing optional, as it causes all the mentioned problems and they are not small .