I think it is more appropriate to state that someone is looking for a house but all landlords he meets will move his front door every day unless he pays tripple rent.
My analogy would be that unless you pay tripple rent you are not allowed to sub-let (connect more PCs with official addresses, atough you could always get married (NAT)) or start a small shop in your garage (put up a Warez sorry Web server) Moving from a volume charge service (dialup) to a fixed fee service (DSL) I do not find it that unreasonable to in some way limit the amout of Internet you can consume.
"If a LIR is obliged to assign address space (is it?),
I don't think so.
wouldn't it make sense to oblige a provider to route it"
I have always assumed that IP addresses is a comodity ISPs hand out with their services. If you buy service from an ISP then you get a reasonable number of IP addresses to use that service. If you buy a singe-user service, you get 1 IP address, if you buy a LAN service you get several addresses.
or the other way'round:
"If an address space request is made, is the non-willingness of an ISP to route it sufficient grounds to deny the request?"
If you don't buy the right kind of service from me, I am not going to acknowledge your IP address request.
That's the point. Can the customer somehow (e.g. by submitting a ripe-141) force the ISP to assign him a static ip address? Or will it get him nowhere?
In my opinion: Hardy. The ISP may then loose the customer of course bu that that is a comercial desicion. But Hey, I would love to buy a high speed domestic internet connection with some IP addresses to connect my computers, but unfortunately nobody is willing to offer me that yet. -hph