Odd stat # modifiers should be used, but with 2 requirements.
1) No non-random stat buys
2) You choose the PC's race prior to rolling
With these 2 met, no min/max is possible during character creation. But is it worth it/what do you get for doing this?
Currently, having a +4 stat modifier is overly powerful and +6 is a sure way to require an ECL mod. But say you wish to make races with more variety of stats, w/out pushing this envelope... instead of +2/+4/+6, you could use +1/+2/+3 and have a divergent range for racial stats. I have done so for my game, allowing for a wider range of modifiers. Also - there are no mental stat modifiers for any prime race due to fear of creating the 'penultimate - if you’re a wizard you'd better be one of us' races. A +1 charisma, intelligence, or wisdom will allow for the slightly smarter or wiser but without the 1st level overpowered jump (2 bonus spells to a 1st level character is overpowered good, though the impact lessons as you rise in levels) seen with +2 or higher mods.
The real advantage is being able to give out smaller bonuses, for slight changes. A race with +1 dexterity is good but not imbalanced. A 1/2 bugbear with a +3 strength is powerful but doesn't replace/completely overshadow the 1/2 orc.
As a side note, I use a modified system for generating characteristics that mixes random with stat buy, suggested by Maggot (of enworld): initial stats are 15,14,13,11,10,8 - place as you wish. Next, roll 6d6. Every roll of 1 = +1 STR, 2=+1 CON, 3=+1 DEX, 4=+1 INT, 5=+1 WIS, 6=+1 CHA. Reroll any die that would create a stat higher then 18 (before race mod).
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