While I agree with you, I still could not stand using glyph of rake lvling up :\ Glyph of Maul and mangle was a significantly better choice
The times in which a mob ran into more mobs were very few and it would not have been of much benefit. The times when there were 2 mobs on me and I didn't want to waste shred - glyph of maul was wonderful.
Supposedly (I haven't heard anything about it recently) there is going to be a glyph of claw for those who are too low to have mangle and do not want to use rake. After that point I would assume switch from claw -> rake.
Would it be a problem if they gave us a glyph of no-reagent requirement D:?