Cross bracings not installed?

[tnicholson3 (Terry Nicholson)]

Here’s another:

Floor joist cross bracing

I would say about 50% of the crawlspaces I inspect have cross bracing installed between each joist but never compleated. Meaning the top end was nailed but the bottm ends were not. I have also observed that no twisting or movement issues were found and many homes are 20 years or older. Would you consider this an issue after 30 years of no problems and would you recommend they be finished.