I usually play like you do I think - 80-90% pristine ships and a high power fleet. I was surprised by how much I liked my industry challenge run though! Bought 2 destroyers the entire game and in retrospect I didn't need to.
Growing the fleet too quickly is the main problem with an industry/bounty run, because the challenges aren't really there. The bounties scale so slowly compared to how fast the player grows in power that it is more like chore work than good fights, and then when the player has 25 ships or so it becomes difficult to get the recoveries that are wanted. Raising the ship limit is needed not to have a bigger fleet, but just to get the correct ships.
I see the main benefit of the industry skills is explosive, hyper fast growth early game followed by having excellent colonies late game. Also, not giving a single care when a ship blows up is very nice. The main downside is hitting the deployment point cap with less powerful ships... but on the other hand, no AI fleet is capable of stopping an endgame player fleet even with D mods, so it doesn't really matter. Its less elegant I guess, needing bigger ships for the same job. Its reducing endgame power from a 20 to an 18, when all the player needs to crush everything is a 10.