A competent lawyer can find a violation of Federal law violation in almost any impromptu government action, mainly violations of due process rights. The key substantive benefit of making such a claim, piling onto state law violations, is recovery of attorneys fees under Section 1983.

It's easy to see that each example in the article involved improper conduct that hopefully violated state law. State law decisions in each case hopefully would have been easy(ier). Constitutional law, on the other hand, sometimes is hard-- especially when there isn't a decision directly on point.

So, we get qualified immunity, where judges decline to allow the tail of (potential) attorneys fee recovery wag the dog of constitutional law challenges that involve complicated issues of both fact and law. No one loves litigation about attorneys fees except lawyers, and that's key insight in understanding the law of qualified immunity.

An alternate solution would be to adjust the incentives that litigants have to bring Section 1983 challenges in the first place-- possibly by making attorneys fees more generally available to litigants-- so that they reserve Section 1983 claims for those cases where they are truly decisive.

Edit: The article does talk about attorneys fees briefly, I corrected my comment. Thanks.