agreed. SMN is hardly a joke job in groups. If may only appear this way because most strats prefer to avoid incorporating SMN into the strat because of its biggest weakness - speed.
SMN can do most anything with proper consideration of strategy, but it can be hella slow - and most players would want to maximize their time in game and get things done faster. They thus don't apply SMN into the mix unless they have to.
However, as slow as it may be, the SMN approach can also end up being the safest, which is why you have all sorts of strategies that utilize SMN for its safety and success rate as mentioned above.
as such, if anything were to really improve or 'fix' SMN from its current state into greater playability, it'd have everything to do with the BP timer, because its really the only thing that is holding us back.
my suggestions:
1) reduce the default BP recast. Base of 45s would probably be a good enough adjustment, if we consider that BP reduction gear can lower this (if we use the existing numeric value cap) to 30s.
For greater effect, could even do with a base of 30s, with gear able to lower this to 15s. This would move SMN damage speed into a totally different range, which is actually fine since it won't be sustainable with limited MP pools.
OR
2) have BP recast vary according to the BP being used.
They could set this as a static value (like say Claw on Garuda giving BP: Rage a 10s recast if its used, but P.Claws giving a 45s recast) - this system is already used for Waltzes.
OR they could set this as a dynamic value based on the relative level that the BP is obtained and the current level of the player, especially for Rage BPs. Like say every 5 levels above a BP you are gives you a reduction of 5 seconds from the BP recast until you hit a base of 5seconds. (so in such a case, lv70 BP would be 40s for Lv90, 35 seconds for Lv95, before taking into account gear). Astral Flow BPs could always be capped at maximum timer to prevent abuse (need MP anyway).
OR
3) a mixture of both. Have base timer at like 45s, implement dynamic recast timers - allow players to be able to mix up using lower damage BPs more frequently or higher damage ones less frequently. Either way would be faster than it already is and it'd be up to the SMN to manage his own MP before it runs out.
Dynamic recast timers doesn't have to affect Ward BPs because the timers on those are actually fine as is, and effectiveness of ward pacts doesn't follow the same usability relationship that rage BPs have in proportion to level.
..this way it doesn't exactly change what we can do, because what we can do is fine. but how fast we can do it would be vastly improved.