That's actually very common for sonatinas, to have more of a bridging passage in minor than a true development. Sonatina in C by Clementi for example(the very famous sonatina for beginners) has a bridging passage in the first movement that is in C minor briefly instead of a true development. Even some full sonatas(namely the Moonlight Sonata and its first movement) have a similar structure to the typical sonatina form.
And you certainly met your goal. It is easily listenable, simple, but not so simple that it becomes boring, and definitely playable(I'd say it's at about the same difficulty level as the K 545 sonata, though that's just from listening).