I agree with this of course, as it's a no brainer. However I don't agree with the part that this is something that will kill the game before we see it in action.
It's not going to kill the game but it will certainly make it look more bizarre and reduce the variety, it's as if you pulled onto the roads one morning and all of a sudden 90% of the cars are all suddenly Honda Civics because they're the most efficient way to get somewhere, and even if they're then going off-roading they can park in the car-park near the woods and their Land Rover pops into existence...
If you're happy seeing fewer people and seeing less variety, then that's fine, but I think it's entirely rational for people to say that's a bad thing.
Is it really a common occurrence to have small weapons and a long jump range on dedicated combat ships? This is something I've very rarely seen, that's why I'm confused.
Yes, depending on what you're doing. I play PP a lot so this is specific but not restricted to PP. If you've got to undermine somewhere distant you may decide to re-spec your FdL for maximum jump range and sacrifice weapons/SCBs etc. slightly for that and a fuel scoop (for instance) because you can get to the system and engage PvE against the transport ships there. There's a trade-off though (and that's part of the challenge) in that if you get seen by a human player you could be in a bit more trouble. With instant ship transfer that trade-off is gone because you can get there even faster (thus reducing even further the chance of being seen) and still have a ship rammed to the gills with weapons that can keep it's D-class FSD online ready to HW out if needed. Less thought/planning needed and less challenging.
Entire games are built around player choices affecting gameplay (MMOs where a class is chosen, games like Deus Ex where you level up certain abilities (augs) etc.). In Elite it's already nice and easy to swap from one "class" to another - I'm not sure why that aspect of gameplay is so anathema to people. It's like being able to swap from a healer to a tank, instantly and at will in an MMO - it seems an odd choice and bizarrely seems to contradict the point of the SLFs. There's a lot less drive to make my T9 capable of surviving in a fight if I only ever have to fly it for one leg of any haulage missions.