Because they have no rights beyond their lousy 3 months tennancy!
The law is a chocolate starfish for them.
You can not expect someone to care for a house they have 3 months security in.
After 5 years in my rented house i have come to the conclusion i will end up being remembered as one of those dreaded tennants.
He can keep the lino we have put into the bathroom and kitchen at our own expense.
The roof leaks but i really don't need another dodgy builder like the one that supposedly fixed the electric in my daughter's room. I never challenged him on that one. It wasn't worth the aggro at the time. One of the sockets works now anyway.
If we had a decent tennancy ... we could put our own laminate in. And put some fresh paint on the walls. But a tennancy that gives us 3 months? You got to be joking!

So the next time you ask yourself the question as to why private tennants seemingly don't care for the places they live in ...

WOULD YOU CARE IF YOU HAD 3 MONTHS SECURITY?
Oh do comment ... I feel so much better now that is of my chest :-)
Crazymental: You're joking aren't you. Only ever had one decent landlord in 25 years of living in the UK. I'm repatriating in January. The law in my home country allows for a minimuum contract of 3 years. 15 year contracts are available too if both parties deide they get on enough. The social housing waiting lists are long in my country. But it's peanuts compared to the chance i have of getting subsidized rent in the UK.
Sue J: Very much in England. I have a verbal agrreement. I don't do agencies. They charge me for the privelege of keeping them in a job. Get real!

WHY ????

The answer is the same as why we treat bus stops, parks, and other public services the way we do.

It is because we have inflated self-importance, and think that our time is far too valuable to worry about keeping things tidy or in good order, we think that others whose time is worthless should run around doing all those menial things.

That's why we always say "THEY" should ...... sort this place out ........ clean this place up ....... provide better services etc.

There's only one of "US" who is important, and there's so many of "THEM" whose time is worthless.

So of course we should never do things for ourselves - THEY should do it for us.

three months? its usually six months. the trick is to find a decent landlord who cares about the property and is not just bothered about having the rent come in. you should see the house my friends mother has just signed a lease on! she's had to go to environmental health and she's not even in the property yet! lol anyway, regarding your improvements, seek legal advice, most landlords are willing to come to some agreement about lowering rent in light of improvements you make, however its best for you to agree in writing before you make improvements, most landlords also dont just give you notice to move after the initial secure tenancy has passed. they would rather the house was rented than stood empty whilst they find a tenant four times a year! if your looking for a longer security tenancy then i suggest the council or housing associations. you still have rights, he can not just evict you, he can not up your rent with out going through the proper channels, etc. your still protected. presuming your in the uk that is.
edit, just read your reply. i know where your coming from and a decent landlord is hard to find. i had five for just the one house a couple of yrs ago. and never knew where i was, i too wont touch an agency with a barge pole. they cause more problems than landlords realise, its a lazy way of being a landlord. i'm lucky at the moment, my landlady is fantastic. why dont you speak to the landlord about your issues instead of just moaning about it to us? if your good tenants then its extremely unlikely he will want you to leave.