There would be perhaps only a few areas that were instanced......sector space would be a thriving giant mass of space where there it would take ages to 'Trek' across ho ho ho.
The planets may not have been as MASSIVE as the WOW 'planet' but I am sure they would be FAR larger than the squares that they currently are. Oh and you would see other people on the planets not just you and your away team/team mates.
Episodes!!! Far more than the 2 Episodes and 1 patrol per level that seem to be the average in STO.
The graphics would be terrible, and would never even be slightly improved, even five years down the road, and after two expansions.
/Facepalm you think they would use the same engine ?...fail....no this would be a real MMO made by a real Game company we would get a bang for your buck and 1 more maybe slight important thing....IT would have been COMPLETED...........
If Blizzard got STO, the Science class would get more buffs while the T4 Cruiser's turn rate would be nerfed from 5 to 3 because "5 is too fast" Klingon's cloaking would never work in combat and they would be qouted at saying "cloaking is overpowered so we know it needs fixed but we cant fix an already overpowered skill"
Not to mention, there would be zero customization, everything in game would only be based on a handful of templates that we would see, over and over and over again.
The graphics would be much much worse, but well themed for their purpose. The game wouldn't be released for 3 more years yet, and the community would be filled with 20x as many idiots, proportionally speaking.