Sorry, but this is just not true.
It's true that it takes a lot of resources to maintain and upgrade many different products.
The Xeltek programmer I own was first released a couple of years AFTER XP 64-bit was released, and there was a large base of users (including myself) clamoring for 64-bit support from Xeltek for a long time (with the above posted quote their general response). They basically made the decision not to bother with putting ANY time into offering 64-bit drivers except with newer models they released. This has nothing to do with the latest OS support (unless you consider a 2001 OS as the latest) - it's just a lazy and/or stupid business practice - and I don't doubt they lost some previous customers because of it. They certainly lost my business.
So you know their business that intimately you can make the call that they are just being lazy, and that there are no other factors involved?
What if they have looked at it and it simply does not business sense for them to do so?
How "large" is that base of users who actually want that support really? A few dozen people on a forum having a whinge maybe?
What if trying to update and maintain that old programmer as well as all their new ones would strain that company resources so much that ALL the products and support would suffer? Or heck, the company is then stretched so thinly resource wise that they ended up losing rep, sales, and eventually folding. Then where will you be?
The model you are complaining about, the SuperPro 280U, dates from 2003, making it 10 years old
Sorry, but the reality always comes down to does it make business sense to maintain older products, and for how long. They are not stupid or lazy, just making a call that it's not in best interest to update a 10 year legacy product to the latest O/S.