It's to try and persuade people to rush a little more. A lot of people save because they feel that if they rush, they will die after the round is over and lose all their weapons and stuff. It's been working pretty well so far, I have seen a lot more people go for defuses/guard the bomb because they know that as soon as the round ends, they are immune from death so they get to keep their stuff.

It also means that since they have those items, they have more money for the next round.

I don't understand what the problem is