The problem is, if they were doing it on consecutive days, they would run the men's race. That's how it's usually been.
Saturday: women ride a short course in central London while members of the public ride the sportive
Sunday: the men ride the London Surrey Hills Classic.
The pro women therefore could only ride the proper course if they forgo the Classique, much like the skiers I referred to eschewing the FIS' World Cup pseudo-Vasaloppet in favour of the real one.
The fact of the matter is, the sportive is what brings the money in for the organisers, because shutting down part of central London isn't cheap. So every year it raises great frustration that the women are palmed off with their pan-flat sprint stage (doubly so because of the typical problem that we get good coverage of pan-flat circuit races and not good coverage of the interesting courses) while the men get to do a proper course with decisive hills. If they alternated year by year, so, say, 2021 the women do the crit and the men do the classic, and then 2022 the women do the classic and the men do the crit, that would be much more readily accepted I feel, because there does remain the need for the sportive in order to keep the event profitable, however in conjunction with things like Innsbruck (where the elite women weren't allowed to race the Gramartboden climb because there was a sportive on it to take advantage of the world championships DURING THE WOMEN'S RACE - both removing an obstacle from the women's race AND lowering its potential audience), Bergen (where Mount Fløyen was not included in the women's ITT), Doha (where the women weren't allowed to race in the desert and just had a pan-flat circuit race in front of no fans), and Tokyo (more problems than I care to mention right now) it becomes more of a frustration that the women are not given a fair chance to show what they can do in racing.
So the main reason the Classique survives is because it can be satisfactorily run alongside the sportive without further disruption, essentially. For better or for worse, because ultimately, you know, it has survived.
The Tour of Scotland is a shame because it was perhaps doomed from the start with some terrible weather on day 1 of its first edition annulling it, as a result it hasn't had the chance to establish itself so it's an easier race to sacrifice. I hope it comes back in some incarnation or another. Especially if Anna Shackley turns out to be really good and we get a nice climby race, because the Tour of Britain only ever really rides through Dumfries and Galloway which looks to be the least geographically interesting part of the country from a cycling perspective. I know things like Bealach Na Ba are not likely because they're in very remote areas, but there's definitely parcours potential up there. I guess however that away from the larger cities - most of which are away from the bigger obstacles - they might need either one of the ski resorts in the Cairngorms or some whisky distilleries to host in order to get the best event?