If the mockups are boring then you have done your job well. The problem is that mockups that stand out, are what gets steak-holders interested. Some of my design work involved selling concepts, and the ones that sold were those that broke the UI conventions in some way. Those features that broke the conventions were then set in stone! Instant regret.
Uniformity is bad! They want bright colors, low contrast text, and each page to be unique. If every page looks the same then they obviously are paying you too much. This is how lots of print designers get started in the web-industry, and wowing people is the main objective. UX doesn't come into it.
The other thing that I've found happen, is business requirements sometimes further complicate the UI. We had a simple app that was a report of damages as part of a return process.
This was mandated by the project manager to be displayed as a progress bar. Sofar as a vehicle that was 100% fucked would be 100% complete. I tried to push back with exclamation points for damaged areas, but progress bars were already sold to the customer.