Azraeel, if you're trying to be "aggressive" by attacking the enem'ys main base and essentially raiding it, then the question is not about reclaim, reclaim is an afterthought. Attacking enemy's main base is not exactly "aggressive" gameplay. Aggressive gameplay is spending resources to gain map control. Attack an enemy's main is attempting to "end the game", which inevitably if you fail will yield certain benefits to the defend for a comeback. Its not really worth it, because you're targetting buildings that can be rebuilt instead of the COM which is what you should be targetting to end the game.
If you want to promote raiding on main bases, then HQ and t3 mex should have lower HP, so that leaving them unprotected and raids as you are suggesting are more punishing. "Raiding" of the main bases is fraught with risk, not because of Reclaim, but more of the fact that you are investing lots of mass into it, and probably not going to achieve much, because almost everything is shielded or has high HP.
If reclaim is significantly reduced, then after you've reached t3 then is not much benefit in fighting for map control at all, as by the time you've exploited the mexes you've just won, the enemy could have made a game ender. There is a certain point in the game where even building t3 mex, puts you behind and the mass is better spent into a paragon or mavor.
Put it this way. A capped t3 mex costs 5400 mass and generates 27 income, it takes 200 seconds to pay itself back. For every 100 mass you invest into gaining that mex that's another 5 seconds added.
Lets say on the average map you have 8 safe mex, then that is 216 income, to build a gameender costing 240k average lets say as a rough estimate, that would be roughly 1100 seconds to complete. With the extra 27 income then you'd build it in about 1000 seconds. So you are saving 100 seconds by getting that mex, but then losing 22 seconds to accumulate the mass to build that mex, then another 5 seconds for every 100 mass spend to take that mex, meaning that if you have to spend more than 1500 mass to take that mex, then the investment is not worth it.
The reason why reclaim is important, is because it offsets the investment that you put into taking that area of the map, and in some circumstances is actually more beneficial than the mex itself as the reclaim value generated is more than the initial investment. Reclaim is also good in promoting efficient mass usage of units. If there was no reclaim, then the person with more income has a much greater advantage, than the person who has less income, and the benefit of microing your units more efficiently isn't as great.