I've said all along that, if the closed season is about fish spawning, the dates are a bad joke. As it stands there's a very good chance that pike, and maybe perch, spawn before the season closes. Then you get to June and find the chub and barbel are still spawning after the season opens.
The proposed closedown of May and June would probably cover the cyprinid species better, for a greater part of the country, than the current dates. It will leave the pike and perch absolutely high and dry though.
If the closed season genuinely covered all coarse fish, it would run from February into the end of July. Then, if you were truly protecting fish spawning, you'd have to consider the Salmonids. That would further cut down times the rivers were open.
As opposed to your thinking, I'd propose that anyone wanting anything other than big extensions to the closed season, is actually acting in their own interests. It can be dressed up in any way you like, but unless the closed season is extended to cover all fish spawning, it's all just a sop. It suits some people, they think they see a benefit in a closed season and they like it. It doesn't suit others, they see the flaws in the logic of it and don't believe there's any benefit to it. Much depends on the part of the country live in, the nature of your local rivers and whether salmonids are present.
My part of the world regularly sees chub and barbel spawning after the season opens. One week after the coarse season closes, the trout season starts, including being able to fish for trout with worms on coarse fishing kit. The river gets no respite from the minimal angling activity in normally sees.
It's hardly surprising that many folks in similar situations think that the closed season is a bit of an illogical joke.