Does the pollination vastly increase the disease vector exposure, both for the contracted hive and all the insects near it?

It certainly does for the bees. All of the hives are in very close proximity, traveling thousands of miles on trucks, for days at a time. The bees are under a lot of stress, mites and diseases spread among them, and some hives don't make it.

Transmission to other insects? I don't know, but I kinda doubt it. Verroa mites were introduced and spread by commercial bees back in the '60s or '70s, but they're entirely endemic at this point. Some native bees are / were harmed by them, and others - based mostly on grooming behavior, actually - aren't much, or even at all, at risk. As someone above pointed out, native and honey bees mostly have different food sources, so they aren't generally in close proximity to each other. Furthermore, the bee diseases of which I'm aware are really, really specific to bees, so I doubt that, say, butterflies or ladybugs or something would be harmed by anything bees carry. I could be wrong about that, though: I'm no expert.

By far the worst threat to native insects, however, is the destruction of native plants and natural habitats. Urban encroachment and landscaping are minor factors (and please plant native plants in your yard: it's great to do), but what's harmed native plants the most has been the farming practice that comes with Roundup Ready™ and similar crops. Previously, fields grew (native) weeds, and had margins where native plants took advantage of irrigation runoff and fertilizer overspill to run wild. Now, farmers broadcast spray weed killer over everything; their genetically-modified crops are immune, but every other plant in the vicinity is destroyed.

While I'm on the subject of bees, my beekeeper uncle doesn't believe Colony Collapse Disorder is a thing. Or, rather, that it happens, but has thoroughly mundane explanations, and any kind of mystery about it has been ginned up by the media, or by beekeepers looking for compensation from the Ag Department. His explanation is that bees are fed, split, and trucked more than they ever have been. (New pesticides maybe, too, but he doesn't think they're much of a factor, since they're not sprayed during pollination times, when bees are in the fields.) All those things stress the bees, and weaken hives; weak hives (as they always have been) get taken out by wax moths and diseases.

His opinion is that old-time beekeepers haven't changed their practice, despite putting their bees under greater stress, and that young (and most amateur) beekeepers don't understand bee behavior well enough to minimize stressors or notice the signs of distressed hives. He innoculates for disease waaay more than he did forty years ago, minimizes feeding (honey is much more nutritious than sugar), and I've rolled up to bee yards ready to load the trucks, only to have him - based on his sense of the weather, and how the bees behaved when he cracked open a few hives - wave us off because the bees wouldn't cope well with moving just then. I don't know enough to evaluate his theory, but I give it credence, because his hive yields aren't any different than they have been for the last fifty years. CCD just isn't an issue for his hives.

Anyway, there's my over-long comment, and I've only got started. Bees are fascinating creatures.