Rude Boy hasn't even crossed 3M in the US after 4 years. Applause is at 2.5M so the difference in sales between the 2 songs is nothing. And they have a similar amount of points on Mediatraffic.
As for RR vs. DWUW, DWUW had more airplay in the US and did pretty decently globally and actually went Platinum (and was not certified 2X Platinum thanks to streaming points like Russian Roulette).
RR was the 21st best selling album of 2010 vs ARTPOP was the 25th best selling of its year.
The discrepancy between the two is minimal.
Add that in to Last Girl on Earth Tour's like $40M gross to artRAVE's $85M - $100M gross (likely) and well...
I still hear Rude Boy on the radio a lot. I've heard it at least 4-5 times in the past 6 months.
Sales weren't the best for sure (I think it's almost at 3 M), but it's not forgotten. Her Top 10s are remembered because she's kept herself extremely relevant. It makes it easier for the GP to remember your old songs when you're still able to get hits in the present.
