Do you ever wonder?

I don't think the OP is really asking for comments about his individual choices, but why are some artists incredibly commercially successful and others not?

A few examples:
Rolling Stones vs. the Kinks
U2 vs. Gang Of 4
Stevie Ray Vaughan vs. Buddy Guy
Grateful Dead vs. Quicksilver Messenger Service
Eric Clapton vs. Jack Bruce

Everyone on this list attained commercial, artistic and critical success, but the first named became megastars and the second named did not. In sports and other competitive fields a person's willpower and desire are major determinate factors, but I'm not sure that's the answer here. Then again, it's called show business and some will naturally know how to work the system better than others.

My 8 year old daughter loves Disney Channel. Seems like every attractive teen on a show that can carry a tune to any extent at all there these days also gets pushed as a recording artist.

I do think Miley Cyrus has talent and it will be interesting to see where her career goes. And how about them Jonas brothers?

I suppose appeal is totally in the eyes of the beholder. One thing for sure, if your selling lots of records, somebody out there likes you.

Remember also that the "pop" in pop music stands for popular and often has little to do with artistic merit, which is all very subjective anyhow.

One thing I've learned as I've gotten older is that most things that are in fact popular generally have some merit mixed in although often it can get lost in the mix.

Metallica; please go away!

Kiss
Queen
Spears
R. Martin
McCartney solo

Cam3366:

Running the "quircky" test on your entries:

Kiss - quircky
Queen - quircky
Spears - quircky
R. Martin - quircky
McCartney solo - past his prime at 67 now but historically as un-quircky as most any major pop star I can think of, I suppose. Go figure! LEnnon. George and Ringo were more the quircky ones.

MCCartney is one of the most measureably successful singers, songwriters musicians and all around performers of all time. What is there to wonder about there (except perhaps his last marriage and that he has never been all that flashy while doing his thing)?