Nothing wrong with the D70's 10.2Mp unless you want huge prints (much larger than A3). As already said, landscapes don't move, so if you are using a tripod then high ISO performance is irrelevant.
There doesn't seems anything wrong with your lens either!
This review by SLRGear is very complementary.
That really only leaves technique!
Speaking from my own experience, when I upgraded from my first DSLR and kit lens there was only a slight improvement in the resultant images and the difference was not the quantum leap I had hoped for.
It was only when I started looking closer at my technique that I realised that right from the beginning I had been the biggest limitation in image quality.
I'd recommend anything that helps with the learning process. A course, a book, a bunch of photobuddies. Whatever works for you!
If I went back to my 20D with kit lens, I could get far better image quality than I did when I was using them.
However, I don't regret upgrading because as my technique improved then I was rewarded with visible improvements in image quality.
So, what to upgrade...
Unless you need the high ISO capabilities of a modern body, then I'd recommend upgrading your lenses.
Look back through your images and see if your favourite images are at the long end or the wide end of the kit lens.
Use that to help decide which new lens to get.