I think part of the problem is that, as a company, they don't differentiate very well between their top-of-the-line ESP instruments and their lower-cost LTD models. IMHO, this lowers the perceived value of their flagship ESP series. If you go to the Fender website, the Squier instruments are in a totally separate category from the "real" Fender basses. ESP gives the LTD models equal billing on their site.
ESP also makes look-alike versions of some of their models in both the ESP and LTD series, which further causes confusion. For example, the Tommy Stinson signature ESP costs $3,500.00, while the LTD version goes for around $900.00. Visually, they are almost identical; and to someone unfamiliar with the brand, they are indistinguishable. Same for their Vintage Four (and LTD 204) basses.
I love ESP basses and my 1980s 400 Series PJ is one of my "keeper" instruments, but I'd never buy an LTD. There's absolutely nothing wrong with them, but then I've never buy a Squier, either. Maybe that makes me a snob…I don't know. For the money I would spend on a new LTD or Squire, I could get a better quality used bass from another manufacturer (a MIA Peavey, for example). In fact, my used 400 Series ESP cost less than a new LTD 204.
Price and availability definitely play into it too. It's hard to convince an American buyer to spend the same money for an ESP P-Bass and and a MIA Fender instrument. IMHO, the quality is equal, but ESP hasn't established itself well enough in the market to charge that much. I'd love to own a Tommy Stinson PJ, but there's no way I would ever spend three grand on one. For that kind of money, I could buy one of the original Fender basses that the ESP trying to emulate!