I don't really think that Resto Shaman is Broken.
It is not the best healer at the moment, but you can heal quite well in 25 man raids.
If it comes down to 10m raiding, your healing spells get quite weak, and you really rely on your cooldowns to top the hps meters. Ascendance, HTT and SL are awesome in 10m mode, however, if you can not use them to their full extent it will be a "wasted" cd in terms of overall hps.
Nevertheless unless nobody dies because of not enough healing, you shouldn't really bother about your healing. The output may seem low, but in a lot of situations, a resto shaman can save your raid (High group or tank damage, which needs to be healed up really fast).