RDM got the mana cost changes to its ST rotation because the math stated it bluntly: with perfect 100% uptime of LD the standard rotation had a maximum time limit of 15 minutes. Each Verraise ate 4 minutes of that time limit, making any situation where the RDM needs to use Verraise anymore then once results in the RDM bottoming out and becoming useless, any fight that would last longer then 11 minutes (like E4) would result in the RDM bottoming out and becoming useless if even one Verraise was used. If the RDM died they became useless. Regardless of skill level this is what the math said. Personal experience did not matter, this is what the math and the logs stated.

So SE listened to the RDMs who complained and were throwing out ideas on how to fix this issue (such as suggesting throwing in a verwater or verblizzard spell that would leech MP, or putting a MP leech on the melee combo), ran the math themselves, and opted to reduce the mana costs of the ST rotation to compensate as a quick fix. They also made reprise useful as a ranged attack for when you are forced into constant movement due to mechanics like the ones in E4 or E1.

Now it takes a really stupid team that is somehow not wiping but still dying a lot to bottom out a RDM