The win rate listed on that site was something higher in general as well - it's pretty obvious that people play them because they're "the easy class" in Arena comparatively from all the evidence there.
Besides, from my standpoint they're just no fun to play against in Arena. Their entire shtick is anti-arena - no other class requires you to consider their 2 mana ability when making your choices in how to build your Arena deck besides Mage and Rogue - and Rogue takes damage to use theirs and is "victim" to Taunt on it's use - mage is literally minimal tempo loss for incredible card advantage.
[Note: I also find Burn heavy Red in MTG to be incredibly shallow and boring too - resource denial can be a fun mechanic but mindless "boom, boom, boom" resource denial especially with NO REAL COST is inherently wrong. Hell, look at how rarely MTG makes some sort of recurring damage without some sort of card cost [or dramatic mana cost, not a trivial 2 mana (which MTG vs. HS would be more equivalent to 1 mana in MTG since hitting 2 is trivial)] tied to it, without damage rolling over between turns.]