As much as I disagree with the first-past-the-post electoral system which elects the UK government in Westminster, I am totally supportive of the sovereignty of Parliament in choosing the Prime Minister. It is natural and generally accepted that the largest grouping of MPs in Parliament select their leader to be Prime Minister. The post has never been directly elected, and one can see interminable wrangles likely if a directly elected PM did not have the support of a majority of MPs.
The current legislation providing fixed-term election intervals is a welcome change from the previous system where a general election could easily be called whenever the PM decided.
Calling for a general election just because the majority group elects a new leader is not, in my opinion, a reason to further disrupt the country. Circumstances in which a General Election is called early might include the outcome of 'Brexit' negotiations, but prior to that event, it seems like empty posturing by minorities seeking to make a political point.