That's partly because people are freaking out about BIP148, Segwit2x, Block size limits, "Core", etc. They're diversifying in case Bitcoin dies, and Ethereum is the logical next choice for many because it's next up in market cap and seems to have a more stable team.

It's fun reading the controversy at http://reddit.com/r/bitcoin (censored) and http://reddit.com/r/btc (less censored)

It also takes some reading to get the hang of what 'smart contracts' and the 'Global Java Virtual Machine' are :)