Even then, if Warfare or the magic school associated with your desired magic damage increase is maxed, getting points in Polymorph and in turn dumping the extra attributes into the damage increase stat relevant to you gives nearly the same benefit as the weapon specializations.
Everyone has a 95% accuracy rate base so single hand specialization only helps vs folks who dodge a lot.
Increased crit multiplier on 2h weapons COULD be very impactful- were it not for autocrits (backstabs) not working with that weapon type, and base crit rates being very low. Still, it CAN be meaningful, if you had a rager (someone enrages you, you ignore being silenced and beat enemies down with your 2h auto attacks), no matter how niche and debatable in practicality that build may be.
even 10% crit chance doesn't make a huge statistical impact on your damage stats, so unless you're going Lone Wolf Ranged is still not all that great, and the same applies to two weapon wielders.
Basically, the bonuses aren't large enough to justify taking them over other abilities, especially when compared to dumping points into say Necromancy for the life leech, or Polymorph for the CC, utility, and extra attribute points, or virtually anything else. Even dumping an extra point or 5 into summons will likely lead to more damage and better survivability out of your team than just the "moar damage" and minor bonus the weapon skills provide.
But hey that's just mho. Don't let me stop you, and if you absolutely love them and can't live without them, I'd love to know why.