More time allows the tank type troops to make more of an impact before needing the back up. And it allows those strangling archers to plunk away at more gold and elixir
Do we all really want this?
Less time insists you make good decisions on the timing of troop placement and a sence of rushing is incorporated because attacking under pressure is a skill that can adapt.
So I say. DO NOT increase the raid times .
You have the time you have at a young th because you need to it to get better. Just like a boxer. If you do not train, 3 min feels like an eternity after round 3 (you fight in desperation) but, champions go 12 rounds. And the greats use to go 15!