15000? I assume that is with a brew, since the highest I've seen is 6k, with the "once every 5 hours" AF3 set proc on a DC monster without any particular resistance. When the average nuke with Shiva, level 5 merit BP and MAB atmas is 3-4k, pulling out numbers like 15000 doesn't hold any weight at all. (And this if 4k on mobs without resistance. Resistant mobs cap you out at like 1-2k nukes every minute)
Still, I have no complaints on the actual damage numbers on SMN. (Except that Shiva nukes for 2k on Panktrator and Odin 2 hours for 2k on it). The problem SMN has is everything else.
For example low level pacts. One way to view them is like low level weaponskills. They should become useless. Or you view them as magic spells due to the MP cost, and then they should be separate timers so that you just like a RDM can apply blind, paralyze and slow without it taking 3 minutes to do.
Currently it is viewed as both. It costs you MP, to just apply slow and some damage and disable your DD ability for a minute. If a WAR doesn't have to pay MP for Fullbreak, why should SMN? It's a WS that already costs you your DD move so it has a huge penalty without additional MP involved.