I think it is cheeky to park outside someone else's house for weeks/months on end. If you know you will not be moving that car for a while you know that you are making it awkward for someone.
It might be perfectly legal and you have every right to park there but, in my opinion, that makes you cheeky and inconsiderate. It's something I would actively avoid doing -and have avoided doing in fact.
You're not 'making it awkward' for anybody at all. Just because they have a favoured space on the public road that you also wanted - and you happened to get there first. If you don't have private parking (or aren't nearby to be able to use it), your car - like theirs - will have to be left somewhere on the public road when it isn't in motion, so why not there?
If somebody doesn't prioritise or can't afford a home with private parking, they need to understand that it really is an equal entitlement for anybody with a legal vehicle. I think you'd be hard pushed to find somebody who has travelled afar and decided to occupy that space for no other reason than to annoy you. It's a convenient space for you, but you'll also find it's a convenient space for them too.
As for those who live near an airport/major station/big shopping centre, I'm sure you would prefer to have the premium spaces that happen to be nearest to your homes left available for you rather than for non-locals - but why criticise them for 'being too mean' to pay to use a public car park when you could equally pay to use that same car park? You have far more regular opportunity than they do to grab and keep that space and thus enable you to benefit from free, convenient parking for the nearby amenity than they will. Surely you realise that, if you choose to buy/rent a house within easy reach of a very popular amenity, it will be.... popular?
Be dispassionate about it: there is a public road which offers free, convenient parking for the nearby airport/station/shopping centre/whatever. Why should you have any more right to it, just by virtue of having bought/rented a house on that street, than anybody else who also finds it convenient?
If you'd bought somewhere in the absolute middle of nowhere, you'd never have any competition for parking - but you also wouldn't have the convenience of the popular amenities close by.