Rob
I actually used to use 25 watt bulbs in my vacuums. Like you, I wasn't satisfied with the brightness of the 15 watt bulbs, especially in some vacuums & powerheads with designs that restrict the light coming out somewhat. The problem I had with them is that they barely lasted more than 2 months before having to change them! And that's a problem I NEVER had using 15 watt bulbs. It's almost as if the vacuum itself burns them out prematurely.
For that reason alone, I use LEDs in my vacuums now. And I can totally see how incandescent appliance bulbs will be obsolete in the next 5 to 10 years, considering LEDs last so much longer & use much less energy.