I don't think anyone will water down trading arrangements because who stands to benefit from that approach? If the EU is willing to force a watered down deal because of politics then how will that benefit EU citizens?
The UK represents 19 smaller EU countries leaving the EU so it is already an almost catastrophic loss for them in terms of its size. A punative trade deal would make it even worse.
If you wanted to sell cars, planes or anything else, would you choose Europe as your target market or the US or China? I know the EU is large but that isn't important because we don't sell to the EU, we sell to countries in the EU. The only way to grow is to target growth in those countries but European growth is flat, absent or shrinking in some places.
I read an amazing statistic the other day, Audi sells more cars to China then it does to the entirety of Europe and it has been growing at blistering pace. Growth in EU car sales meanwhile is actually falling! In some EU countries those sales are so small that they barely register on the map.
So if you were a car maker in this case, would you want a trade deal with the EU or would you want a trade deal with China? But, just imagine if there was an option for both.... Isn't that the entire goal of Brexit?
We just need to remember that we are leaving the EU, not Europe.