MAME has gotten technically worse? Are you on drugs? Especially the new super high res artwork support is fantastic, see here for a quick example with Space Invaders:
High-score saving support was taken out because it was an ugly hack that caused stupid bugs. It is being replaced by the save-state support anyway, so if you want to record your scores just save the state (or enable auto-save, then it gets saved automatically when you close MAME).
AVI recording was replaced by MNG recording. MNGs combined with the WAVs you can output can be converted to an AVI if you want.
As for the config thing, I have no idea how many configs you need really, because MAME supports general controls that are valid for all games anyway. Maybe you need special controls for 10 games - big deal to redo those.
And MAME hasn't taken an overly-serious approach as of late - it was always like that. It's even in thier FAQ.