The following opinions are written from the perspective of someone who plays both DPS and Point Defense guardian for a competitive tournament team.
I think everyone can agree that there was definitely a need for changing Tome of Courage, prior to the change there was no decision when it came to elite skills, ToC was far better than ToW and Renewed Focus. The AE daze combined with the complete heal allowed for only a small window in which you could be Moaed or boon stripped and interrupted.
After the nerf I played around with the different options. A defensive guardian with +boon duration could still use “Stand your ground” and get off a full heal or you can use Hallowed ground or sanctuary. These abilities can essentially guarantee a complete cast but use a very valuable utility, two of which have very long cool downs. Tome of Courage is still a useful elite but it requires much more planning/effort to use it effectively.
Renewed focus has become my new favorite elite for my point defense guardian. One of the primary values of the book was to keep yourself alive while waiting for help to arrive and renewed focus does this job pretty well. However, when you are actively using renewed focus you do not count as being present in the point, I am not sure if that is by design or a bug. Traited for virtues and boon duration you can get off a nice set of boons on allies while putting out blinds + aegis + stability + 3 condition removal.
After the patch I gave Tome of Wrath a test for the very first time, and seeing as though no one was running it before the Tome nerf I have no idea why they decided to remove its stability. The damage is mediocre, the #4 ability is decent I suppose since quickness = good, but the #5 has to be one of the most worthless I have come across. You are rooted in place for several seconds for a 600 range AE KD with some decent damage if you manage to get it off and have anyone still within range.
While not having the power of the old Tome obviously weakens guardians overall, point defense guardians are still in a good place overall with stability utilities and b/c renewed focus is such a solid alternative. However, DPS guardians are now left without a truly viable elite since most do not spec extensively into virtues, limiting the value they get from renewed focus or having to make a major utility sacrifice to use ToC or ToW effectively.
I don’t have any great proposals for solutions, I just want to get the idea out there that the book nerf hurt DPS guardians the most and has kind of pushed them into unviable territory when compared to other profession options.