And they still have budget limitations, hence the constant modern day England!
Whats the point of having a machine that travels through time and space when you do neither?

They basically waste their whole effects budget on one or two episodes, then have to spend the rest of the time doing the modern day England stuff!

As for limitations of the time, you are completely wrong on that.
TV shows and films being made at the same time proved the limitations were far higher than Doctor Who pushed.
It was (and still is) purely budget related.
BBC does not have the budget to have sets and costumes as good as its peers for a whole series.
If they spread the budget out more, the sets and costumes would suffer, but they would still be better than the original shows!

If you want a guy to to stay in modern day England all the time, fighting aliens, why not just create a whole new series?
A timelord who does not timetravel is like doing a Flash tv series and having him walk everywhere!

Snarf is shit. His death will be rejoiced!