I understand the tournament has a storied tradition. I also understand his excellent record there but is it really necessary to play this? Coming off of a nice win in Monte Carlo with no time off. In addition, Rafa also plays other tournaments that make no sense at all. Bangkok in 2010 and Tokyo last year. Just doesn't make sense for a guy who basically lost at the 2009 French due to injury and has lost/withdrew from numerous other big events due to injury.
He has to play a certain no. of 500 events - it's mandatory to play 4 though Monte Carlo can count as one of your 4. Which 500s should he play if not Barcelona?
Tokyo is also a 500 - it's a good one to play in the lead up to Shanghai - he needs to play a 500 - again - why not that one?
As for Bangkok, that was a one time thing mainly because he got paid a ridiculous amount of money and got a package holiday deal as part of it i.e. him and his 10+ friends got a beach holiday in Thailand in exchange for some PR
and official engagements from Rafa. Coming off the US Open I don't blame him for taking up that holiday - chilling with his friends on a beach, going fishing and then playing a few matches - win/win. Definitely not something he should do long term though.
In the last few years he only plays mandatory tournaments and then "warm ups" i.e. Doha and Queens before Aus Open and Wimbledon. He's even played just 3 out of the 4 500s. So his schedule is pretty slimmed down. He's learnt from his mistakes to some extent. If I were him I'd skip Madrid though - don't think he will however.