Good location, great infrastructure, cheaper than France and Italy, pristine beaches (one of the pros of the lack of industry), a lot of beautiful historical buildings. After the WWII and West-East split, the vast majority of tourists were from the Communist block and visiting Croatia became a habit for them. The Slavic language is a big plus for Poles, Czechs and Slovaks. There's 1 million of Czech tourists every year (Croats even have jokes about them). It has been largely undiscovered by the Western tourists so now they're all rushing there. Croats are pretty good at organizing events, they have a bunch of summer festival that attract the younger crowd.
Croatia was the 2nd most developed region in Yugoslavia (after Slovenia) and if it weren't for the war, they would have joined the EU much sooner. I'm from a neighbouring country and I happen to know quite a lot about them. Trust me, they're not boring. I guess you're not from Europe? I seriously cannot imagine any European calling Croatia boring. Poor - maybe (hardly) but boring - no way.
Let me tell you, I am from Poland and many people in my country are not very rich and we cannot fly to places. Many Poles can simply drive down and even better I can understand Croatian. It is hot, sunny, and on the beach. It is such a beautiful place, I cannot wait to go back. This is probably why!
Gorgeous seaside, crystal clear water, great weather, amazing historic sites, great architecture, delicious food, friendly people, inexpensive when compared to Italy, Greece or Spain
It's very cheap (and it shows..) and has some good scenery.