If you don't see the benefits then you haven't used the rifle in the same way as those who do see the benefits. If you hike, and not just from the ATV up the tree stand, every pound is very important. If you hunt in dense areas, a shorter barrel is important. If you need a longer LOP than the 5'8" grunt wearing full winter gear that the stock was designed for then it may be important.
Anymore, there isn't really a benefit to modifying milsurp rifles. They have increased in price and factory rifles have fallen in price. You can buy quite a few sub 2MOA rifles for under $400 today, some of which will hold sub 1MOA. Back when sporterizing was in it's prime that wasn't the case. Milsurp rifles were far less expensive than commercial rifles. Taking a $25 rifle, stoning the trigger, hacking the barrel off, reshaping the stock, and adding a longer recoil pad only really cost that of the recoil pad. I think a lot of sporterized rifles are done so in poor taste or with poor execution, but I can certainly understand why many of them were done.
If we are talking about doing this today I have a much harder time appreciating the benefits of buying and modifying a milsurp when commercial rifles are available for similar or often lower prices.