1) Engineers have kits with shield generators and they get abilities that allows them to set up shields.
2) It would define the Engineer Class as more important to team setup.
3) They make fights last far longer than they should.
4) It shouldn't necessarily be possible without a noticeable power source.
5) It makes fighting almost totally risk-less.
I can understand personal shields on Borg, but they have a lot of cybernetic gear on their bodies, and their bodies are literally batteries. Nothing on non-Borg validates their existence. Their removal at some point and a healing nerf of 1/5th would make Ground Combat more salient.
The problem of flying through content is another story though.
All generators do is recharge personal shields, beside without shields you be toast on advanced or elite.
The generator indeed does do that, but it could instead be used as a shield emplacement. Body armor should be your actual protection. Personal shields could just be a certain type of armor with a power pack. They could even expand Body Armor and give it Add-on slots and make personal shields one such possibility to enhance their usefulness.
These changes would make tactical game-play more necessary for ground combat after the changes in season 4, harder difficulties won't be a huge problem if Body Armor is buffed a bit.
I only want ground combat to make you think before you shoot is all. I think the removal of personal shields and their re-purposing along with the remaking of ground combat will do just that.
I don't think personal shields are going anywhere, since there are missions in the game that use them as plot devices. Also, personal shields pre-date the Borg. They existed in TOS, when two aliens boarded the Enterprise to continue a duel that spanned the galaxy. They had personal shields which blocked phaser fire, but had no visible power source or emitter.
There is a story/explanation for the personal shield. You can catch part of it on loading screens sometimes. An Andorian scientist/researcher invented it. Became standard issue. I don't recall if it emanates from the belt or communicator, but it is an evolution of star trek technology and that's why we got it.
I believe it is on the belt giving that is where your character tends to put their hands (follow by a glow) when using a shield charge.
There is also mentions through certain exploration missions that your Personal Shields will protect you from radiation while you do repair. Most notable one that comes to mind is the "Power Station" ones usually found in Delta Volonis Cluster.
While there were no personal shields in any of the Star Trek shows, there was something similar in the Star Trek Animated Series in which a personal force field was used as an "environmental suit". This force field was strong enough, that in one episode is kept a crewman from being cut in half when he was caught in a closing door. So it probably was able to resist some small amount of damage.
Personally, I find the personal force field generators more believable than the body armor. I can buy a force field deflecting energy beam attacks, but armor should be disintegrated by any typical phaser beam. Then again, I'm guessing the armor is reinforced with energy fields.
In game terms, shields provide you with a second "health point bar", which protects your main bar, while armor provides you with a percentage resistance to damage. To change this mechanism would totally change the way combat in STO works, not to mention making it inconsistent with space combat. Many of the abilities and strategies in STO center around penetrating the shields in some way so you can apply the damage to the hull/body. To eliminate this would make weapons like Tetryon beams and Psionic attacks, and abilities like Tachyon Harmonic, effectively useless.
(Also, Ubernaut's TOS episode is a good example, too, although that was not Federation technology. It does show that such a device could fit on a belt, though)
There wsa an episode of TNG where Worf uses his badge as an emitter for a personal shield. It only had a split second of use time, but it was still there. Maybe since then they've reworked the power of the badge? ANd i can see where you're going, and the armor sounds kind of cool, but at the same time constantly having to get armor repaired can be costly an annoying. Having an armor that regenerates like the shields do is a lot nicer.
Although on a side note i'd love to see more types of armor or even shield bubbles like the ships have but around your characters. I'm looking forward to it on the borg as well.