I noticed this a couple of times when playing really close-in games with multiple players- Sometimes it's more effective to simply reclaim an enemy unit rather than destroy it with conventional weapons, since the amount of time it takes to destroy en enemy via reclamation can be significantly shorter than the time it takes to destroy it with guns. This is especially true in the case of stuff like walls, where a squad of five engiebots can take down a wall faster than five times their number in tanks. Personally, I think it'd make more sense if the time taken to reclaim a living enemy unit/structure was more dependent on health, rather than build time.
Having reclaim be so powerful is awesome, as it makes for very interesting tactics with car fabs and such. Fabricators literally just get one or two hit by most units, it's not exactly easy to do It. =P
Not if you drop them right on top of the commander and they're not paying attention. If you're quick enough, you can probably get at least 15 on the ground. 15 Cfabbers reclaiming at one time would definitely be enough to drop a comms health in a couple seconds easily.