@Flet I refer you to HirumaKai's comment from last page: 10% isn't small, its just not as crazy as 20%
All on its own its not small, but to reach it reliably you need to sacrifice a lot. We are talking about fleet composition being dictated to you, hull mods being dictated to you, and needing the skill. Thats three things you need to stack. ECM-superiority is an entire playstyle given all you have to do to accomplish it.
Consider what you get for simply eating the 10% hit? You could instead build expanded missile racks into everything and just have twice as many missiles on a non missile fleet. In fact given how the eccm mod works now why wouldnt you just build that into every ship instead of the ecm? Then you only get a mere 5% penalty and your missiles are all better, you dont need the skill, nor do you need to spend the elite selection on officer gunnery skills now, and you dont have to load your fleet with frigates anymore.
This is in a way, again, an improvement, in that it solves the enemy ecm issue. The main problem that remains is that it simply just does not make sense for players to invest in ecm at all now given what is required to reach the advantage against enemies it really matters for. Perhaps ecm could just be removed entirely.