Here's a profound answer, one that should completely answer your question:
It's a meme. It's truly not that great of a Pokemon.
Now time to go more in-depth. Bidoof is famously memeable due to its expression. Take a look at the picture above and tell me that that doesn't make you smile. It has a cupcake for a snout. How can you not fall in love with a cupcake-snouted rodent, especially when it happens to be our lord and saviour?
Bidoof was everywhere in the Sinnoh early game, meaning people were seeing a lot of it and its memorable cry. This plus the fact that it was a great HM slave made it popular, if only because of how terrible it could be.
It has two great Abilities in Simple and Moody. The first of which can be abused with Swords Dance, and the latter was so broken Smogon banned it entirely.
Bidoof does have a niche in LC with Simple, making it a surprisingly solid attacker. However, it still isn't used all that much, and that's the only tier it's viable in. It's outclassed by Zigzagoon, and it's only used because... you guessed it... MEME POTENTIAL!
Even The Official Pokemon Channel recognizes the sheer amazingness of our lord and saviour. A video titled Bidoof's Big Stand recently came out (and yes, it's official content) and if you weren't convinced already, it solidifies Bidoof as the most perfect being to exist on our puny plane of existence.
To answer the last part of your question, it's because Bidoof created Arceus, obviously. Did Bibarel create Arceus? I didn't think so.
Is that not the face of a higher being?