This goes beyond the original thread subject (agility) but I wish they would allow more customization/upgrading of ships. I get why the new ships are generally better, hopefully they implement some type of upgrade option for older ships to bring them more in line with newer ones.Yeah, there is no ship balance. Ships becoming completely obsolete is fine in the real world, but shouldn't happen in a game. Would rather see some favored ships become unavailable for buy and rebuy then others becoming obsolete.
I'm very much against exclusive upgrades. Every ship should be able to take on every upgrade, provided the ship's stats support upgrade's installation (slots, mass, cooling,...).
My idea for ship customization would be that within reason you could upgrade/engineer the ship hull even more than just module engineering. So for example, you are not going to be able to make a Sidewinder carry 100 tons of cargo or have 4 huge hardpoints. But you might be able to add a small or medium hardpoint, increase base speed and/or agility, maybe add some class 1 module slots and utility slots, increase heat efficiency/capacity, etc... So within reason (primarily the physical size of the ship) you can upgrade/customize. Then there would be the option of 'side grades' like agility focused thrusters where you are trading speed for agility.