I remember the period and some of the debates that raged at the time and, vaguely, the reasons why some software vendors wanted control. At least, what hit the general newspapers at the time. What I saw in the papers was that end users sold their software to someone else when they didn't want the software anymore, or rental companies would buy the software and rent it out, and the vendors wanted to make both situations impossible, somehow. In fact, it was especially in the case of rentals that there was a LOT of argument going on at the time.
None of this yet addresses itself to situations where the lack of software patents has led to "protection with teeth" in the specific case of software.
And you cannot seem to avoid hauling in the 'music industry' when struggling to press your hypothesis. I don't mean that negatively, but I am simply unable to port that into this sphere of seeing this in terms of software. That may be my own lack of imagination. But there it is. There are too many differences in medium, market and market history, and I'm sure this lack of similarity also applies to past case history, contract law, and torts, and the preparation of courts and judges to make well-informed findings, as well.
In any case, I just can't get see your assertion regarding software protection getting stronger by removing software patents. Copyright already exists in the US. It is also enforced, as well. You, yourself, gave an example of this in another post. Patents are, as another poster mentioned, a veritable mine field (and besides that, I already have taken the opinion that patents no longer have much value to anyone other than large companies, anyway, these days.)
What would help is a showing from a developed country (in the EU?) where a similar outcome followed as you say it would, with details in evidence, as you assert would occur here in the US. Namely, where the lack of patents there has led to _stronger_ protections with more teeth in them than here in the US, as a total picture.
To be frank, I think the combination of patents AND copyright in the US has more teeth than copyright only and I cannot see how the removal of software patents would put MORE teeth into a situation. Copyright is one method for some domain, patents are another method of another domain (possibly overlapping in areas) and the two, combined, is more than either alone. Even after the courts have a hand in it.
Perhaps I'm not communicating well and am just blind enough that you cannot seem to reach me, either. It's a chasm I can clearly notice, but cannot clearly see how to bridge. I know you were trying to make a clear point that others would understand well enough. Maybe others got it and I am just not smart enough to do so. I wish I were better able to follow your point.