I believe it's because so many are convinced that SP-only is the only way to go and that dynamic sql is slow, dangerous or some other misconception. I don't think dynamic sql is slow and I don't harbor the misconceptions. I know some very sharp SQL developers who just throw up on the idea of dynamic sql. I don't necessarily share their views (nor do I share the polarizing views from the other camp as well).
One of the big reasons I prefer SPs is management issue of data access across all applications (which might be written in different tools) hitting the data. The code management issue will usually scale out better with SPs.
A few months ago I worked with a vendor in San Diego on a database and reporting application. Initially, the developers were generating SQL code from C# statements, and had been doing so for years. I gave them a walkthrough of how I use stored procs to test data access outside the application - I expected some resistance, but instead found that they liked the approach better.