but I watched it last week and it’s time for it to be over.

Like most TV shows it ran to long.

The show stopped being funny. It's all canned laughter and idiotic plots.

IMO, what happened was that the show was doing well until the main three actors - Johnny Galecki, Jim Parsons, and Kaley Cuoco - demanded and got huge pay raises. In order to afford them, the show's producers cut back on the writing.

Just my opinion...

Including that they took cuts in order to make sure that the other actors that came on later got increases.

You don't "cut back" in writing.

Why did it stop being funny? I watched every episode up until about two years ago. To me and other people, the show stopped being funny.

The bulk, some 240 episodes, were directed by the same guy. The main creative staff and producers were the same throughout the run. The storylines grew and changed. Some aspects of the characters stayed the same. Some didn't.

You changed. You just didn't care anymore. It was that simple. It happens with most shows that run the length this did.

I always enjoyed it just because I identify so strongly with Leonard. An awkward nerd who managed to marry the smoking hot goddess.

But I'll admit, I won't mourn the loss; it's time for it to be over.

It changed significantly over the years. In the first couple I was surprised it wasn't sparking outrage since the entire over arching theme was being smart made you undesirable and being pretty was the preferred condition. There was even a hint of suggestion that one could not be both. They started changing that about year 3 and brought in a succession of characters that were smart AND attractive. Then they started marrying them off and having babies and it basically became your basic sitcom of silly people being silly.

I cannot imagine how tired/stale it would be after ten more seasons...

Also, I cannot stand laugh-tracks (which TBBT used heavily) -- I find them as noxious as nails on a chalkboard.

...The use of Bob Newhart as a glowing Obi Wan Kenobi was hilarious.
...Interaction between Sheldon and Stephen Hawking also great.
Many other funny moments.

The dialogue was not only witty, but fast. Jim Parson's rapid fire explanation of the rules of rock-paper-scissors-lizard-Spock is a classic! And the characters evolved over the course of the show's run. And, they consulted real scientists to make sure the science on the show was correct, right down to the formulae on the white boards.

It was a well written, well produced and well acted series. Sad to see it go, but I thought they did a great job in the finale.

and the writers left all the characters in a good place.