There are several reasons why this is the case, but one strikes me as obvious and important. In most cases, ASPs that have adopted and hosted products developed by software vendors have not spent much time beefing up their vertical market business development. Rather, any vertical market prominence by such ASPs is often a byproduct of sales. On the other hand, ASPs that have built their own software typically have focused on a vertical market applications and the vertical market business model. I believe this type of targeted vertical approach is necessary.
Many ASPs try to offer the least-customized version of software that they host.
By doing this, they are not learning the business of their customers and, in my opinion, are not laying the foundation they need to become a software partner with their enterprise customers. I don't think that ASPs need to be experts in a vertical market. But to convince their prospects that they can be an effective software partner, ASPs at least need to understand the primary business problems that exist in the vertical markets they target. It also means building up a sales staff that understands the targeted market. But there are payoffs.