I've always had a bit of an issue with guarding. Before Abyssea, there were some things that I tanked, nothing overly hard, but literally every time I would get a guard skill up, I'd state it out to my LS. Even today, other MNKs in my group have adopted the same joke.
Getting guard skill ups is horrible. Even worse, at CAP, you'll only guard 10% of the time.
I liken Guarding to Shield skill. Both are meant to be a defensive capability when a mob is attacking you. In my length of time in FFXI, I've seem at least two changes to Shield skill, upping rates of blocking, increasing skill gain, and even a spell to increase shield blocks and reflect damage. If Guarding has changed at all, I don't recall this happening.
PLD were meant to be a tank, and it's understandable that they should have more reliance on shields. Times have changed though, and MNK has become a big contender in the tanking field. I think it's time to give a second look at Guarding skill. Make it better in some form. I'm not sure exactly what to change about it, but it's one of a MNK's two defensive capabilities (The other being Counter.).
Please consider taking a look at guarding skill again. I'm sure many MNKs would love you for it. =)