I don't know, it still always struck me as rather arbitrary to limit it to variable effects. I mean, an Empowered (thus 4th level) Bull's Strength for +6... not exactly what I'd call shenanigans. Most spells that give static bonuses are not that outrageously powerful when multiplied by 1.5 AND increased by two spell levels.
Now if you want to bring up metamagic cost reducers... sure, that's more shenanigan-y, but it's not the Empower Spell that's the offender then, it's Easy Metamagic, or Incantatrix, or Divine Metamagic, or whatever.
That said, it's my firm belief that metamagic was messed up horrendously by the designers of 3.0, and the transition to 3.5 hasn't had much of a positive effect. There's very few metamagic feats that would be worth using EVEN IF YOU GOT THE FEAT FOR FREE. At least, metamagic feats right out of the box, that is.
So the designers introduced metamagic cost reducers, which brought us the wonders of Divine Metamagic cheese. Now that's not the way this should have been handled. Instead of introducing ridiculous increases in spell level (seriously, +3 for Maximize?), some other mechanic should have been found, such as reducing effective caster level, costing more spell slots, etc. Maybe even a mechanism whereby every caster could freely alter certain aspects of a spell (range, duration, damage etc.) while paying consecutively more for higher adjustments? This has been discussed with regard to Extend Spell variants
here.