The Times thinks they are a good idea:
Open primaries are part of the solution. If candidates had to win the support, as individuals, of thousands of local voters, it would increase the quality of MPs, hold them to account and ensure they were more independent.
Open Primaries would mean the end of ministers who sit in the House of Commons or House of Lords.
Why? Because the skills required to get elected are not the same as those required to administer. That's why in the US "political administration" and "elected office" are two only slightly overlapping career tracks.
In the US, "politicians" get dug in at a local level, and use family, union (rarely), business (commonly) and party (occasionally) connections to rise up the electoral level.
"Political administrators", the huge swathe of top and middle level administrators in Federal and State agencies, who trade on ability rather than charisma, climb a different career path.
This system does not give "power to the people" - it gives it to people with the money to campaign. For primaries to work in the US you need a lot of money for local advertising.
I don't think this is in any way better than the UK system. Here, at least, people need a certain level of ability even to get through local party selection committees.
UK Parties are able to define themselves. American parties - where in most states anyone can declare themselves a member of any party, and in some states anyone can vote any party's primaries.
The result is literally tens of thousands of elected idiots, most of whom are not know to their constituents, who do little of what is regarded as "constituency business" here. And who, after all that, often have limited power vis-a-vis the separately elected executive officials.
Sure, we need change. We don't need change from a defective American system.