In 2009 Ferrari, BMW and Toyota decided to test in Bahrain to avoid the miserable weather coditions in Europe; the rest of the teams went to Jerez.
For two days the teams in Bahrain couldn't hit the track because a sandstorm made it impossible for the emergency helicopter to fly. In the meanwhile, McLaren, Renault, Toro Rosso, Red Bull and Williams had four full days of test in Jerez. The other three teams waited and took the two days they had missed on the following week.
While I understand that wet weather is far from ideal for testing, and in this particular year Spain is subject to plenty of rain and strong winds, given the experience in 2009 I don't think that it can be considered a good reason for moving the test to Bahrain. Plus, with the difficulties that the new engines could bring (and that some teams have indeed had), I would have expected that staying close to the factories would have a key criteria for this season.
Anyway, the key thing is to have the cars back on track!