There's always a dilemma about whether to do the upgrade yourself, or let the buyer put their stamp on it. The worst thing I found when looking at houses was new kitchens that were not to my taste. I couldn't justify pulling them out but didn't want to live with them either. So we didn't offer on those houses.
Here, the issue is how to create the space for a bigger kitchen with its own seating (it is still nice having a separate formal dining room too). So, if your parents could get an architect to draw up plans for re-jigging the space to achieve a bigger kitchen - and deal with all the other oddities people have mentioned - that would be really reassuring and helpful. Potential buyers could get builders' estimates on those plans.
If I could visualise the new kitchen space, I'd much rather choose my own fittings. Obviously I'd expect the price of the building work and kitchen fitting to be taken off the sale price, compared to similar size and price places that are already lovely.
For other buyers, who can't be bothered with the work, delays, mess etc. it would be better to get the work done now and put in a 'current' style, reasonably neutrally coloured kitchen.