LOOGYs are extremely prevalent as MLB pitching staffs have grown to be 12-13 as the norm. Like it or not, it's no longer a gimmick, it's a well used strategy to glean talent from the margins.
I do agree that the bullpen needs to be improved, however the margin isn't the concern. The concern with the bullpen is lack of depth at the 7th,8th,closer roles. One of the best/cheapest ways to develop that talent is to promote youth to the bullpen ALA Trevor Hildenberger.
There are many "flaws" to this stratagem:
The very definition of LOOGY is a guy who is there for only one out. Ergo, he's not good enough to pitch to more than one batter (or for that matter, a RHB);
12 or worse 13 pitchers on the active roster unnecessarily restricts the bench. Results in the lack of substitutes. How about having a RHB available when the opponent inserts their LOOGY? It sure would be nice to a dependable hitter to turn the tables.
Infielders in the OF. Or any other sub-optimum use of players. Necessitates having the Danny Santana's of the BB world so every possible position can be manned if required.
Regulars get less rest, The alternative: see above.
Pitchers don't have to learn to fix their own problems--they look to the dugout to be "bailed-out". Maybe even "blame" their replacement for yielding the "big hit".
Standards were lowered for the pitchers.
All of this so the manager can demonstrate his "managin' "skill.
Last, but not least, the use of "lesser players" to try to squeeze a marginal team into the playoffs and perpetuate the baloney of "Ya' never know".