should take place in 2007

Not having it take place in the current time would be a huge missed opportunity. Look at just how much the world has changed in the past 5 years!

#MeToo
"Defund the Police"
George Floyd and subsequent riots
political unrest
Russia
China
Harvey Weinstein
North Korea
cyber crimes
diversity and political correctness to the 1,000th degree
wokeness

To name just a few!
There's so much material they could use to build stories and material around (both comedic and dramatic)....all which has taken place in current times.
Why the f-ck would you avoid that gold mine of material...and instead have the movie take place in 2007????

Besides....their ages in the movie world don't necessarily need to align exactly with the actual passage of time from when Lethal Weapon 4 hit the theaters until now, LOL! All we need to know is.....Riggs is an aging detective (like he was recently in Dragged Across Concrete)....and Murtaugh is also....an aging detective. That is all.

Both are still in good shape for their age, so it's conceivable....as long as the audience can suspend a (little bit of) disbelief. If people can manage to do that....this movie can be made and enjoyed.

I'm not sure people can compute that in their heads though. The fact that people actually think the shaved on the sides and poofy-poodle on top hairstyle looks good.....gives me very little confidence in any generation after mine.