Bl were not shinning that much in group. Their slo/haste always remained quite inferior to the shaman/enchanter ones. Beaslords were simply easy mode soloers. Unlike bards, wizzies, druids that needed to apply risky and dynamic kiting strategies, beaslord simply tanked and spanked opponents.
BL Slow was ~60%. Shaman/Chanter Slow was only 65/70%. That's not much worse.
Their haste, again, was only ~10% behind Shaman/Chanter Haste (on both counts IIRC Chanters were slightly superior to Shaman, who were ahead of BL).
What made BLs shine in groups was the fact that their skillset allowed them to have a lot of synergy with other classes, especially as a DPS class who could replace a Chanter in groups with good pullers, still Regen mana, still Slow Mobs, provide additional buffs, and do good damage (or, at least more damage than a chanter).
Remember, by the time PoP rolled around SOE was fervently trying to get rid of the Holy Trinity resulting in tons of MOBs being immune to Mezz or charm (i.e. Plane of Storms).
They soloed almost like mages with the earth pet, with small differences : they could share teh beating with the pet and they had good debuf. Their mana regen was also another asset.
I knew good mage almost able to do what BL did, but it was way more risky and you needed more skill.
Mages didn't catch up to Beastlords IRT soloing until (to a lesser extent) OoW, and to a greater extent DoDH (I think that was the expansion where they got their temp pet on steroids).
By that time, MOBs were already hitting for ridiculous amounts of damage and mitigating Attack Speed Slow effects.
In a sense BL were applauded because they were the perfect easy mode soloer.
See above. Necros, Bards, Druids, and Wizards (post 35 or so, when they got their snare) were all perfect easy mode soloers unless MOBs were immune to their effects (Bards got nerfed in PoP). That's not why they were applauded. In fact, all the classes I mentioned above were superior to Beastlords.
The BL were clearly inspired by soloing shamen, post 45 shaman could actually play almost exactly like a Beaslord. But they had a much weaker pet (puppie my love) and so a much larger part of the tanking was done by the shaman.
They were a Monk/Shaman Hybrid, so yea.
According to SOE infamy record i strongly believe that Blords will be so much owvrpowered that crusaders will be jealous.