Model legislation is not at all confined to conservative causes or nefarious lobbyists; but I have seen the issue in the news lately (see also Indiana Law Blog) with respect to the American Legislative Exchange Council (ALEC). ALEC is an organization through which conservative model legislation is routed.
As I said, there is other model legislation. A prominent organization is the Uniform Law Commission which strives to provide model, non-partisan legislation on a variety of subjects (Indiana’s delegation includes James Bopp and Vi Simpson so, it’s got range in terms of partisanship.) Various institutions and lobbying interests advance their own model legislation.
As a legislative drafter, my primary concern with model legislation was that it created a “magic word” view of the topic. Often, the legislator advancing the model legislation in Indiana wasn’t comfortable making the call on what the bill should or shouldn’t accomplish; they had a general notion, but when it came to addressing particular difficulties, they were uncomfortable modifying the language. So, if the model legislation interacted with existing Indiana law in some troublesome way, it was sometimes difficult to know how to resolve the problem.
A hide-bound devotion to the language itself, sometimes bordering on idolatry, obviously is not a good approach to legislating. You have to grok the idea behind the language so you can make the language serve the idea rather than blindly serving the language as an end in itself. This is more difficult when the legislator is not the one creating the idea or the language. The idea, at times, comes from some group who creates the language and then is not available for consultation when it’s time to modify the language. And that can create a problem.