Honestly Semi-Limiting a card right now does more damage than limiting it. If you Semi-Limit this, it means I can't run two copies of TTH, Hey, Trunade! or Enemy Controller.
They did limit onslaught, so, why wouldn't they limit DNA Surgery? The reason they gave was that it was hard to deal with (something like that). With onslaught you could at least attack and activate monster effect but with DNA Surgery +
Buster Blader, the Dragon Destroyer Swordsman you can't change battle position and cannot activate monster effects, this is worse than onslaught.