monsters,honestly,this list actually reminda me of marry the night which was hell classical!! applause is getting the sucess it needs,honestly,it doesnt really deaerves as much as marry the night or other gagas singles.....
lol applause is like number 6/9 mostly, people like the video, sing it, talk about it. it may not be a smash hit like poker face, bad romance etc... but its a hit! is it a flop? hell no! Are there better songs on the album? I really think so!
Well, it's complicated.
In one hand, numbers aren't an indicative of quality, as your examples pointed out. There are many, many classic albums that didn't do very well on the shelves, but are considered masterpieces nowadays.
On the other hand, today's market, with internet and the possibility of counting every digital and physical copy sale, has made numbers relevant. They sort of measure one's popularity and acceptance on the market, and, like it or not, music is a product, as is the artist (at least partially), so the more one artist sells the bigger the budgets (s)he will get and the more space on TV, Internet, Radio will be at his (her) disposal.