The IEPs are only really used on services that most people book in advance anyway, and they work ok for typical audax type bikes. They’re a much bigger problem for chunkier MTBs and loaded touring bikes and stuff.
I do worry some of the well-meaning grumbling and campaigning around them scares people into driving when they otherwise wouldn’t.
I think it's one of those relative risk things. If I can't get my bike on a train to get to an audax or similar, then it's only a bike ride. If it's the first (or last) leg of a tour, not only is getting the bike and luggage on board likely to be more difficult, there are likely to be more serious consequences of failing to get on.
Unfortunately, the long distance routes served by the IEPs are biased towards the sort of cyclists who are travelling with luggage and have to be somewhere on time, be they tourists, students at the end of term or whatever. Or at least they will be after the remaining commuters have either given up or invested in a Brompton or second hack bike.