Clément "Kaposhipi" Ruggeri, of the FFXIV EU Community Team, replied in the Summoner Feedback post with information explaining why SMN, MNK, and RDM changes were made.
First of all, the main objective of the PvP action adjustments made in Patch 4.45 was to buff jobs with which it's relatively difficult to win, when compared to other jobs of the same role.
The difficulty of winning as a Summoner is the lack of burst and survivability. As such, it has been decided to adjust the potency of Energy Drain to improve both burst and self-heal.
We are aware that some of you are requesting Tri-bind or any kind of CC ability to be (re-)added, as well as some changes to Bahamut, but for the moment we would like to see how this change to Energy Drain feels. Please try it out and do let us know what you think!
Summoners might not be too happy with these changes as Bahamut bugs do not help the players be consistent with burst. However, the feedback in the OT has been passed on to devs and they can evaluate for a future update.
Wind tackle is the only mobility skill for Monks and although it can be used twice in a row, it has a rather long cooldown. For this reason, it was shortened so that it could be used for both offensive and defensive purposes.
Monk mains will welcome the mobility buff, but the community is unsure if this change will be enough to put them on par with DRG and SAM due to the frequency MNKs can burst. Also, monks are not as durable as their counterparts.
Shorter cast time for Vercure will enable a more usable emergency heal.
Since Red mages have to dive in melee range for their physical/burst combo, its potency has been increased to balance out that risk.
More burst is nice and the shorter cast time helps the red mage support the healer, but a reduced GCD on certain actions and TP reduction on Corps-a-corps and Displacement would be welcome. (See this post)