I would have thought that if it were just custom and practice in contract writing with the intention to prevent IP from laying fallow too long that the contract language would have adjusted over time to block recurring stuff like the movie critic in costume stunt which ends up with the IP actually laying fallow for decades.
Contractual language has evolved. But ... you have to remember a few things.
1. IP is considered much more valuable now than it was back in the day. The Dick Tracy movie was done in 1990, so the contract (with attendant rights re: IP and sequels) predates that.
2. It does cost money and time to maintain rights- depending on the contractual language, you might have to have actual screenings, etc. While Warren Beatty seems to have arrived at a clever solution, it's still not costless to get people together, shoot it, and book time on a station.
3. No contract is perfect; for example, look at the current dispute between HBO and Paramount over South Park. HBO thought they were getting exclusive rights to South Park for their streaming service (during that time period when Paramount was in turmoil and didn't care much about streaming; see also Yellowstone). So now there's arguing over what constitutes a "season" and whether an "event" is an episode, a movie, or neither.
In general, the issue of rights comes to the forefront because people are maintaining these rights in the hope/assumption that someone will buy them out of the rights at the end. The D&D movie rights were another example of this. A lot of times, when there is an issue of clouded rights, you just end up seeing money and/or producer credits handed out.