This is, imh[umble]o, a must-have tanking glyph. In dungeons. there are many many many times when you will be pulling groups of more than 3 mobs. Frequently (with exceptions), these are groups of 4 (3 and a pet, 2+2, etc). This glyph allows one of the pally's best aggro-grabbinbg spells to hit what will 90% of the time be "everybody in the group." If there are extras, or if you grab an add, consecrate will hold the adds that aren't being Hammered long enough to start HotR on an add while still hitting 3 additional mobs, maintaining aggro on everything in the process.
Another benefit is one will see a noticeable increase in the effectiveness of SoL/SoW/SoJ procs. 3 procs of SoL heals for a good 1100 on me, with all 4 goin in the 1300 range, and SoW way-more than pays for itself. A proc of 3/4 happens much more frequently than a proc of 3/3.