Our units stand slightly out from the wall due to the uneveness of the wall rather than space for services. End panels are wider than the base cabinets so instead of having the end panel so it is flush with the door it is flush with the edge of the base cabinet. The small gap then left at the back is hidden with beading. Our kitchen is white so easy to find beading that blends in fairly well.
If you are ripping a kitchen out and the walls are bare then just move the services. My mate who is far from even remotely DIY capable hired a chisel attachment for her drill and dug a channel in the wall for a new gas pipe going in!
We are having an Ikea kitchen fitted later this year, both my sisters have them and love them.
The only time the lack of service void is likely to be an issue is if you lived in a 400 year old stone house and no wall was remotely straight or flat.
The deal is Ikea don't make a cover panel deeper than their cupboards.
the lack of services void is not a problem (its a fake issue bigged up by rival companies and poor fitters) you just run all pipes at plinth height and then straight up - and tehn the units sit against the wall like normal and then the worktop fits as normal.
my Ikea kitchen is still fab after nearly five years - pic on my photos