Ground Assault being.. Apothecaries and Sorcerers? Don't they already have enough extra stuff going on without being able to cap on top of that?

Also Toaster is spot on. If they get 2/4 then half their units can cap.. that's like 3/7 for us so Banshees, Fire Dragons and Dire Avengers. It only makes sense. Scorpions being cappy, now THAT would make for some interesting situations.

Ground assault being Storm Shield equipped assaults/CSM equivalent.

Banshee's scream may make the players view become unclear and maybe also stop some specific actions?

ground assaults are a subtype of two classes ...

LSM get an assault marine whos discarded his jump-pack in place of having a storm sheild
CSM get a traitor marine whos dumped his ranged weapon in favour of a big sharp melee weapon

since the CSM ground assault is a traitor marine who already should be able to cap (chaos tactical eqv.) the devs are thinking about allowing the LSM ground assault class the ability to cap as well

so technically the arguement should be why should LSM get 2 "classes" that can cap, when the CSM would still only have the 1?

The number of players on a given map is fixed, and divided equally. In order to be concerned about how many classes can capture, you'd have to assume that all of the players of a given faction will divide themselves equally among all of the available classes.

Is that a sound assumption?

Wait, so only one or two classes are going to be able to capture points? Why? Excluding support and heavy (which in my opinion make no sense to exclude), there are plenty of games that have hovering, or flying, or extremely fast characters and vehicles and everyone captures points with no issue.

So why is this a thing? Have they said?

It may need to change for every race, it is one way to incentivize people to play Tacticals over picking specialists (apart from Tactical already being arguably the best and most flexible combat class) - but currently everyone just plays Tacticals for this reason.

The ability to roll off into the sunset whenever an assault lands by you isn't enough?

well ... if you look at the fluff, most space marine are tactical marines, the others make up smaller percentages of the force

and they decided to limit the capping classes to prevent the fast highly mobile classes from being used as the cappers .... games would be over too damn quick otherwise, why build defensive lines and slog it out if the jumpers could just bounce past everyone and take the points

Yep. In a nutshell, right there.