By category the bikes you listed (CBR125 - Ninja250 - RC390 - CBR500) are all light Sport Touring (ST) bikes, they're just dressed in Sportbike plastics.
Agreed except for the RC390. I've never ridden one, but I understand they're definitely the sportiest of the beginner bikes, with the lowest bars, highest pegs, and hardest suspension.
would you really call them sport bikes? isn't the whole draw of sport bikes the crazy acceleration figures etc, the small entry level ones got none of that so it makes sense why a cruisers more enjoyable you're not really missing out on much and you're gaining the extra usability etc
Pedant alert!
I rented an NC30 (400 cc version of the RC30) in Thailand many moons ago, and it was 100% sportbike. Only made about 60 hp, but had scalpel-sharp handling and sounded amazing. It had good acceleration for its size (and compared to the ubiquitous scooters over there), but would still lose to a V-Strom 650 in a drag race.
In fact, I'd say most 600 sportbikes also have pretty mediocre acceleration from 0-50 km/h or so, as they don't make much power below 8-9,000 rpm.
To me, the draw of sportbikes is the focus with which they're built. They're designed to go as fast as possible around a circuit with corners, so need handling, grip, acceleration and top speed (aerodynamics) balanced in a way that makes best use of the engine size they have for that purpose. Ergonomics are designed to aid in that (hanging off, ground clearance, tucking in), but make little concession to comfort.
As for trading it in for a cruiser, if that's what floats your boat, have at it. Cruiser sales are still relatively strong for a reason: it best fits what lots of folks want out of a bike.