Well, with the area's long history of being under Rome and Venice (the Habsburg Empire got it only in 1848), it would be much more justified to call Austria and Hungary (and Yugoslavia and Croatia) the barbarian invaders :-) But what Austria-Hungary did was industrialization and belle epoque tourism development (Abbazia/Opatija).

3) the food is local, simple, and delicious (Italian and, I suspect, Hungarian influence)

I doubt it. The main food influences must be Italian, Croatian, Dalmatian (in that order).

At least in mid-April, there seemed to be about 10 of us turistas in the whole city of Pula.

Along Croatia's Adriatic Coast, the summer tourism season is very much marked - with a reason: especially in autumn and winter, the weather changes dramatically from sunny to one with strong winds (Bora, Yugo). In summer, the Western coast of Istria (and the island chain before it) is packed, too. Opatia also wakes from its slumber, and serves as port for miriads of boats taking tourists for round trips to the islands in the Kvarner Gulf. (Highly recommended should you visit again, BTW.)

_{*Lunatic*, n.
One whose delusions are out of fashion.}