I can't say SMN would MPK people any more or less than another job, It all depends on how bad the player is, not the job.
Plus, SMN is plenty useful in Walk of Echoes, It acts like campaign, Buffs are AoE. SMN Can Hastega every DD in range, Blink/Phalanx/Stoneskin (SCH Can too - But not Hastega), Earthern Armor, Ifrits beef Enfire. Theres a lot a SMN Can do, as well as Safely DD.
Not saying other jobs can't, Just saying you don't always have a D*mn tank to heal.
P.S: People don't do Walk of Echoes 15 for funsies, they go for Gil drops like this:
http://wiki.bluegartr.com/bg/Nomkahpa_Mittens
http://www.ffxiah.com/item/10990/engulfer-cape
http://www.ffxiah.com/item/10958/nefarious-collar
These items maintain a decent price, Unlike most WoE Items which plummet, because these are from a flux a bit harder and a little less done.
Of course, One of the biggest money makers still comes from a lesser Walk, the PDT Head, But Nomkahpa Mitts are pretty wild.