This is EXCACTLY my situation and it's so utterly infuriating! There is clearly a HUGE market for the' larger' screened iMac, or at the very least, a slightly more 'Pro' version. I'm putting 'pro' in quotes, because Apple these days seem to simply like to label their top of the line/most expensive products as 'pro'.
In reality, I think many people who are 'professionals' in the creative industry are very much like you and I are. Moderate income, working either freelance or for companies that have limited hardware budgets. Therefore such people cannot afford to simply jump to a £3000+ 'studio' or similar set-up. We simply want/need a more competent iMac/All-In-One computer. I could just about manage with a 24" screen if pushed, but I certainly need more storage, 3-4tb+, more ports, a little more power if possible and more neutral colours. And preferably within the £2-3000 mark. This isn't asking a lot.
We have so many iPhone/Macbook/iPad/Watch variations, it seem ludicrous that they wouldn't offer an alternative version of the iMac. Absolutely gutting in fact. I've literally been hanging on for the last 2-3 years for this upgrade and now it feels like I finally may have to consider moving on from Apple, which I really don't want to do, but their product offering now just doesn't seem to suit my needs or is far too unaffordable. Such a shame.