It really does Bowers & Wilkins an injustice to compare them to Beats. B&W's been making audio equipment--mainly speakers for the longest time--for years. Beats, on the other hand, hasn't even been around for 10 years?
The P5 has solid craftsmanship. I've tried it too, and I'm sure you noticed it the moment you picked it up. The lambskin pads both feel nice and are practical, easily conforming to the shape of your ears and providing a decent seal from the outside world. It's also great that they detach by magnets--makes swapping them out (and the cable) easy. The overall construction of the headphone is sturdy, due in large part to the metal frame, which the cups also slide along smoothly and silently. And, the sound is nice. Not award-winning, but nice.
You can't judge a product solely on SQ. That's unrealistic. We all choose our products based on a variety of factors, and even if SQ is the primary one, it's not like the rest just disappear. The P5 is expensive, but it feels expensive, and based on the materials, there's some point to the expense. The Beats headphones--for the most part--do not look or feel expensive, and aside from noise cancellation (which other companies do better, cheaper, or both), there doesn't seem to be much justification for the expense.