People are jumping on the hype train because PS3 was disappointing last gen, making it the underdog. People love underdogs.
Or maybe they enjoyed the ps3 and therefore thought the ps4 would make a good console too? That certainly played a part in my decision to get the ps4. I really didn't care about the ps3's sales relative to the 360 and wii. The most important thing for me was to deliver the games, which the ps3 did in spades and I believe the ps4 will do so too.