People seem to be having kneejerk reactions to the profitability of PvE because people sitting in bigger caps can farm lower-tiered faster than farming those of equal tier.
Reducing the reward overall reduces it for everyone including the valid cases where it should remain what it currently is.
Also, you almost have to go one tier below your ship's tier because NPC spawns can be pretty painful and unreliable for mission completion if you're in say a cruiser doing cruiser missions.
What I would rather see, is:
1) Introduce a diminishing effect to rewards when you're over-tiering (ie: Cruiser killing snubs, Battleships killing gunboats) -- A gunboat killing snubs, for example, should be fine and not penalized.
2) What would be the prospects of potentially make it so that mission npcs don't consist of a single type of ship?
If a mission currently spawns 4 Cruisers, make it spawn 2 cruisers and 4 gunboats instead.
If a mission currently spawns 2 battleships, make it spawn 1 battleship and 2 cruisers.
If a mission currently spawns 4 gunboats, make it spawn 2 gunboats and 6-8 fighters.
Something along those lines. Looking at Haste's post, this idea would likely be more for generic missions in random locations and intended to be soloable (less difficulty, less reward, easy to run into over-tier penalty). While missions in specific areas would be more like the current missions (but more difficult) where you're more likely to need a group of people (more difficulty, more reward, harder to run into over-tier penalty).