I agree that the non-specialized suits are not in a good place and I think it has to do with how suit bonuses are applied. There is no bonus on a non-specialized suit and I think there should be. I made this progression picture to show how I feel the suits should be tiered and the names reflect how the suit is bonused. The bonus should be defined by the suit and applied with the level of the skill needed to use the suit.


Lets just use the medium frames because this is what this thread is about.

Standard

Entrencher - One defensive bonus applied per level of assault.
Assault - One offensive bonus applied per level of assault.
Field Medic - One logi bonus applied per level of logi.

Advanced

Weapons Specialist - Two bonuses per level of assault, one for weapon DPS and the other for racial defensive tank.
Close Support - Two bonuses per level of assault and both would be for the racial defensive tank.
Engineer - Two bonuses per level of logi, one for the equipment used by the race and the other for a racial defensive tank.

Prototype

Anti-Vehicle - Three bonuses, one static racial and two per level bonuses geared toward anti-vehicle. The static would be racial defensive tank, one per level to DPS and one per level to racial tank.
Alpha Strike - Three bonuses, one static racial and two per level bonuses geared toward DPS. The static would be a racial DPS, one per level would be to range and one to DPS
Ranged support-Three bonuses, one static racial and two per level bonuses geared toward range. The static would be a range bonus, one per level would be to speed and one per level to DPS.
Medical Support - One static and two to per level bonuses geared towards providing team HP support. The static would be an equipment bonus, one per level of equipment effectiveness and one per level to racial defensive tank.
Logistical Support - One static and two per level bonuses geared towards providing team logistical support. The static would be to racial defensive tank, one per level to racial equipment effectiveness and one to racial equipment fitting.
Anti-Vehicle - Three bonuses, one static racial and two per level bonuses geared toward anti-vehicle. The static would be to racial DPS, one per level would be to AV effectiveness and one per level would be geared towards racial DPS.

I understand that not all of these suits would fit into the racial lore of each race, that is something for CCP to figure out and I don't know what bonus should be applied to what area. These suits would also have different slot layouts from one another and between the tiers. Each suit slot layout would compliment the bonuses the suit has.

The lower tier suits may have more slots but they would have fewer bonuses that improved the modules equipped and weapons used. As the merc moved up through the tiers the suits would lose slots here and there but the loss of a slot would be made up by the bonus received by the suit. The idea would be to make the suit better by having more bonuses that buff the modules used better as the merc levels the skills up. Stats would also change, no suit would have the same HP, speed, regen, CPU/PG resources and this would make each suit unique and give all suits a role to play.

The way suits are now upper tier suits are just the same thing with more resources and it doesn't make any sense to use a lower tier suit because they are clearly inferior to the upper tiers. In the progression I propose the suits are better as you move up through the tier but they are clearly different and do not just have more slots. In fact the upper tier will have less because they are specialized and highly bonused instead of generic and lightly bonused. This just my Idea but it think it would encourage the use of lower tier suits more often because the higher tiers would be expensive and highly specialized and not do as well in every situation as a lower tier suit would.