Yeah, the fact that is very easy to get duds with Glyphs is kind of a problem, but on the flip side the effects scale weirdly (they have little use at low height, but once you get passed stage 5 even half decent ones start becoming seriously powerful)
Also, the multipliers are not that useful and it is often better to used items that increase the base, and very few instances you want the effects on multiple attribute rather than all on the one (unless there all positive, which is rare)
The base for Glyphs may also be a bit of a balance problem but that is a whole other issue