First thoughts are that you must not play in a Logi suit much. "Speed" and "Logi" hardly ever belong in the same sentence unless juxtaposed with something like "lack of". Also Logi are not in the "forward slayer" category. I've yet to see a "slayer" logi build that doesn't depend on the AR (and almost exclusively the TAR in a Cal Logi suit at that). I'm sure there are players who can make that work but when talking suit values that's not part of the equation. As far as WP earnings from support actions are concerned those are down across the boards and even dedicated support Logi are having to resort more 'slayer' activities just to remain in the same ballpark as the last build. The list is too long to repeat here but the TL;DR is earnings potential from all equipment types is lower now than in Chrome (with the arguable exception of the RE and noting that the Scanner is both new and has no WP earnings yet).

Heavies can be front line as easily as assault within the right context. Granted these contexts are more limited than the assault however a well specc'ed heavy can hold his own in CQC against more than one assault (the current use of TAR not withstanding but that issue isn't a suit based thing). All of which presumes HMG heavy as opposed to the use of other weapons, role will alter based on weapon employed. Leaving all the light weapon possibilities aside (I've still seen heavy snipers, heavy shotgunners and heavy AR guys doing work in various matches) the heavy possesses access to the Forge which in addition to it's AV abilities (such as 1-2 shotting dropships and LAVs, as well as eating up non-proto HAVs) is currently a more effective area denial weapon than the MD. The heavy suit will likely become more popular with the introduction of the "commando" heavy which packs 2 light weapon slots and not heavy slot.

Scouts are limited to flaking and scouting it's true but an active scanner, a set of nova knives or a well placed shotgun blast is still quite effective. And the main assets of the scout are speed and scanning/damp. So various forms of flaking are really their intended niche (sniper scouts notwithstanding). There's also the coming cloak which if things hold to EVE style the scouts will get a bonus to fitting giving them more options (and possibly explaining some of the delay in deploying the other racial scout suits). The scouts are also going to be highly effective at both deploying and countering eWar, another aspect of the mechanics which is confirmed as coming but still not integrated into the game.

Assaults are the ever popular "go to" suit, they are the AR of the dropsuit line... however in Uprising they took a bit of a hit as their racial suit buffs weren't well received in general and (the on board rep of the minny aside) they didn't really offer any non-shield tanking options making them take one on the chin to some extent with the introduction of the new weapons.
To some extent the familiarity of the assault suit, combined with it's name and "jack of all trades" base suit values will likely keep it in prominence. And while I fully support the development and viability of other diverse roles it's important to bear in mind that part of this popularity is based on what the players feel at home with due to prior FPS time and is not actually a comment on balance.

Cheers,
Cross