[mmm_grayons]

There's still a distinct meani g of happy. For some reason, though, people are trying to stamp it out; I hardly hear it used in new writing.

[CydeWeys]

It's not remotely as nefarious as that, it's just that language evolves over time and conflicting meanings that cause confusion tend to be weeded out.

[pulse7]

"For some reason..." ...the reason is that today "it mostly evolved into sexual orientation" like another commenter said.

[gilrain]

Interestingly, the adverb form is still mostly used in the joyful sense. "The weather cleared, and the people danced gaily."