Any why should a mage always have the best pet? A warder is a pet which the beastlord has cared for and raised. Personally I think beastlords should have the only pet which can taunt agro off melees. Mage pets are a random summoned elemental not a pet which has been cared for and trained. Back in the day when bst 1st came out their warders were stronger. I would have my warder duel mage pets of similar levels and I wouldn't buff my warder with the DD proc and it would win every time usally ending with my warder still having around 40% life, the mages were super upset about it. It wasn't until after PoP that mage pets really took off and surpassed warders as far as damage and over all tanking capability. By giving Mages the strongest pet combine with the ability to do massive DDs and burn mobs quickly leads to a huge imbalance in classes imo, esp when in the past pets couldn't hold agro off melees. it wasn't as bad when mages lacked the ability to really heal their pets efficiently but now they can just pop a swarm pet and pop a heal and keep up a steady pace. those servants do crazy damage and can take allot of hits before fading, bst servants crumble when hit.
Yimin makes a good point though: Beastlords have a ton of tools at their disposal. Mages have nothing per se. And if you want to get all "lore-ish", I'd still say a summoned, fully controlled servant from an elemental plane can/should out-power a pet that has a stronger emotional bond.