You are indeed right to be angry, I think most answers to your HL models question were too harsh. And you are right, HL can handle a huge amount of polygons, it's just a matter of what computer you are using.
But it is also true that the HL engine will have a much worse performance than Source using the same model. It's not only about physics and nice textures, a lot of things have been greatly improved.
On the r_speeds part, I think it's really not a question of how much does your computer lag with 1000 polys or 2000 polys. Computers today can handle very high polycounts, but not the same as 6 years ago. So when making a "Half-life map", I always make maps that will work with any computer that played the original game with decent performance. Presenting a map to the public that has potential problems in some computers isnt the perfect thing to do. There's ways to make nice brush work with control over r_speeds.
So 6 years after HL came out, we all want to make bigger maps, more r_speeds and put in more detailed models. And the logical way to do so is using the source engine, in my opinion
I agree that we could do without STEAM, but source mapping is just as fun as normal HL mapping, both hammer editors start with an empty grid, and it's just a matter of filling it up. Slaves and Grunts are cool, but combine soldiers, cables and high res textures can be fun also!