Alright lets break this down.
1. F1 now is no more littered with pay drivers than any point in the past. Check out the fields from the early 1990s where you had teams and drivers who never pre-qualified for a race, much less start one. Regardless we do not hold that against the greats such as Senna, Prost, and Mansell.
2. All racing requires money, some have more money to bring, others have less. To hold one series higher because they have a greater number of guys who couldn't get enough money lined up is silly.
3. Le Mans racing is chock full of drivers who are there just because they have enough money to do so. In fact they even have a class for it, LMGTE AM.
4. People can very easily question if it was the car in Le Mans as they can in F1. For instance in 1991, the 787b was not the best car there the Silk Cut Jags were faster, but they ran into problems during the race. Or this year, Audi could have locked out the podium but they ran into mechanical issues. Does this reflect badly upon the driver or the car? Also with driving duties split among 3 drivers, aren't you only as strong as your weakest driver?
With that said, if Webber achieves success with Porsche it will certainly help his career. I also have the utmost respect for sports car drivers and I think they are very talented, but I bet a huge number of them would swap out a Le Mans victory for the rarified air that is a F1 WDC.