In my experience, a "hard shift" is almost always preferable to a "smooth shift" as far as automatic transmissions are concerned. Hard shift means less slippage, less wear and tear on clutches and bands inside the tranny, smooth shifts = more wear and tear on clutches and bands.
All that considered... if it shifts TOO hard you can damage the actual gears which is infinitely worse. You end up grenading panetary gears, steels, torque converters, and such.
As far as what the shop says... unless you know these guys personally, all shops will up-sell you so you will never get a true read on what is ACTUALLY wrong. Front seal, common wear item, i can see that being true if you are leaking fluid. You had to be towed but I do not know how the truck was behaving prior to being towed to be able to tell you if this is accurate. Bearings on tranny are bad is a vary vague statement. Could mean bands, could mean frictions, could mean they just want you to pay them lots of money.
Ok so... What exactly was the truck doing when it left you sit?
