I'm a big vinyl fan myself. Jingle all the way is the only vinyl album the flecktones have released. I was under the impression that the latest, rocket science, would also be released but that didn't see to pan out (though with the online store closed for maintenance, who knows what'll be there when it comes back? I can dream right?). A did manage to find a rare 12" single of sinister minister but that's all.
Béla does have a bunch of solo albums from the early days, as well as Béla with the bands tasty licks, dreadful snakes, spectrum.
As to why, I can't speak for the band but I would imagine it might not make that much sense financial for a band that doesn't exactly sell millions upon millions of records. There's definitely a commitment to quality, with Hidden Land being released on dualdisc dvd (dvd in enhanced sound) as well as Béla's Tales from the Acoustic Planet in dvd-audio (24bit/96, surround). I think you have to remember that 5-7 years ago, vinyl for some bands wasn't popular, instead it was pushing the bounds of digital (SACD, DVDA) which they've done a bit.
edit: I oh just forgot Victor just re-released a show of hands in vinyl; definitely a must buy, solo Victor, just a bass guitar, on vinyl = musical bliss.