Attorney General John Suthers says (rightly, to my mind) that the constitution is for "general principles that govern sovereignty." Stability is the game when it comes to constitutions. Add in voters who might sometimes take a short-sighted view of the long-term effects, and easy amendments can make a mess.
The catalyst for the legislative shift is a recently passed ethics amendment that is chafing state employees. So the legislators are offering a popular referendum to stiffen the constitution while the iron is hot. Of course, such a change would necessarily make the legislature itself stronger. Hard to tell which is pricklier: a shapeshifting constitution or legislators giving themselves more power?