Why Do People Complain About Summoner?
Summoner flows really well, imo.
Everything you do is locked behind Aetherflow, so you'll be working in 60 second increments and within said increments you flow through 2-3 phases, Rouse.. DWT.. Bahamut. Once you understand that the class flows extremely well and works in ~20 second increments.
Summoner also is currently the 2nd highest DPS at the 50-99% range in FFLogs in Savage, with only Samurai above it. If you include the raid dps increase via Radiant Shield, a 2% phys damage debuff that potentially lasts 24 seconds and is on a 60 second cooldown, and the raidwide Devotion buff (2% for 15 seconds on a 2 minute CD) they are easily ahead of Samurais in DPS. They also are MUCH more mobile than BLM and arguably RDM (Dualcast makes every other cast instant whereas SMNs can make use of ruin 2 at what is now only a 30 potency loss compared to 50 before via Ruin 3), do better damage than BLM and RDM, have better utility than BLM and RDM (BLM virtually none, while the rDPS increase Devotion, Contagion, and Radiant Shield bring outweighs those that Embolden brings), and can also resurrect allies now that we are overflowing with MP every 60 seconds because Swiftcast is no longer needed to use a Ruin 4 proc during Bahamut phase... 1 rez a minute should be fine if your group knows the fight.
In other words, SMN flows very well if you understand the class, has the best DPS and utility of all the casters by a solid margin... ESPECIALLY if you take into account their rdps increase via said utility, AND is very mobile. I don't understand why people are continuing to complain about Summoner. Even before 4.1 SMN was in a great spot, but now? Geez man we are insane.
I think the real problem with the class is that it requires thought.