Kapeselus commented the reason the Lurker unit wasn’t included in Starcraft II Beta, and admits some of the developers miss it, but some of the new units cover well Tier 2. From my personal point of view, Lurkers were fun. However, they were expensive, had no attacks while unburrowed, and were easily killed with sweep scan, observer or enemy Overlord detection.

The health regeneration and burrowing ability of the Roach makes it a cost efficient candidate over the Lurker.

Blizzard Quote:
The developers say that Lurkers were taken out because their goal is to keep the unit count of the game as small as possible so that players know their choices and understand their enemy choices as well. They feel that the Roach uses the Lurker’s burrow ability well, while Ultralisks and Banelings have the splash damage covered. Many units took over Lurkers’ roles over the period of development, so they didn’t think they were as valuable anymore. But we all do miss them!

Well this is our point of view. I think that Lurkers should not really be Tier2 in the current build, because they don’t really fit in there and they wouldn’t really be a good counter to Roaches, given the fact that ZvZ is a very dynamic matchup and you would probably still prefer Ultralisks or Broodlords at T3. What do you think about it?