Quartz said:
Consider a Ftr 4/ Wiz 6. She attacks at BAB +7, and her Fireballs do 6d6 damage. Now add in the Practiced Spellcaster feat and her Fireballs do 10d6 damage. But she still attacks at BAB +7. A bit unfair, isn't it?
And assuming it's a specialist evoker, they've got maybe 4 such 10d6 Fireballs per day with a 16 Intelligence (or anything from 16 to 23), probably with better Strength and/or Dexterity than a pure wizard.
By comparison, the pure wizard (evoker) 10 will have probably maxed-out Intelligence of 24 (18 base, +2 levels, +4 Headband of Intellect), and a total of 6 such 10d6 Fireballs per day. Plus, y'know, 5 slots of 4th-level and 4 slots of 5th-level, which the fighter 4/evoker 6 won't have. So 6 Fireballs at 10d6, 5 Enlarged Fireballs at 10d6, and 4 Empowered Fireballs at 10d6 x1.5.
The pure fighter 10 would probably be doing WF, WS, GWF, and Power Attack with a +1 flaming shock greatsword, with Strength 24 (attacking at +10/+5 for 4d6+33/4d6+33 damage, or +15/+10 for 4d6+23/4d6+23) every round. Plus Melee Weapon Mastery and Improved Critical and whatnot (I don't have PHB2 and haven't looked at a copy in a few months, so I forget how much MWM adds). Probably the occasional Spirited Charge too with a lance, atop a warhorse mount or something.
A feat that boosted Base Attack Bonus would be rather powerful, anyway, and easily abuseable.