I'm not a big fan of phils because of the exposed bearing seals. IME cartridge bearing seals along won't keep water out forever. Not great considering many cheaper hubs work just as well and give the bearings more protection.
There are reasons you practically never come across phils outside the fixed crowd and the odd tourer.
Miche hubs have the end-cap seals you're describing, and they do absolutely nothing. I'd rather have access to clean the bearing seals than have grit build up between that seal and a cap.
The reason you rarely see Phil hubs might have to do with a lot: distribution channels, price, weight, to name a few. Although I tend to believe the reason they're not widely used is because nearly everyone riding road bikes today is on a racing-style bike instead of the more appropriate sport-touring style. Simply look at how large manufacturers have catered to silly demand for pseudo-racing junk: cheap paired-spoke wheels, lower and lower spoke counts, CF-everything, removing USEFUL eyelets from frames, etc...