I would love different types of SRVs.
But there is no use for different types, as long as there are no more fleshed out scenarios for them from a game mechanics PoV. What use is a big, lumbering SRV that can carry 20 tons of cargo without some ground mining or similar mission to give it a purpose? What use is a heavily armored and armed SRV, without gound battle scenarios? What use is a long range SRV without some long range ground mission to give it a purpose?
Different SRVs, while sounding pretty cool, would have to go hand in hand with actually fleshed out ground scenarios to use them in. Otherwise, we'd be looking at "re-skins" with little purpose besides visual differntiation.
The need is presently in game, I could easily fill 20 tons of SRV cargo hold when scavenging the man made signatures on planet's surfaces. As for base assaults an ordinary SRV isn't enough for some missions as some ground locations are very heavily defended and are practically city sized, Goliath's are tough too.
The need is already in game, why FD isn't catering to these very real needs is beyond me, they don't seem to know what their players do in game as evidenced by their refusal to acknowledge what players do as opposed to what FD want players to do, the example being passenger missions, they came in and all other mission payments got nerfed despite the fact that being a space bus driver doesn't appeal to all. Passenger missions can pay 20 times as much as a cargo mission, talk about railroading your player base by manipulating cash rewards.