If indeed there is more overt mention of homosexuality in children's playground rhymes, it's not necessarily a recent trend, unless by "recent" you mean 25 years ago (1984). Though some contributors of the Michael Jackson insult verses refer more generally to chanting those rhymes in the 1980s, you will recall that the 1984 date was when that Pop star was burned while filming the Pepsi-Cola commercial that includes a version of his hit song "Billie Jean".

Many of these "Down By The Banks Of The Hanky Panky" verses include references to "Michael Jackson", "various brands of soda pop", Jackson "being burned" {or being "bought up" which I take to mean being "messed up"), and "Billie Jean" (often in corrupted form such as 'beligene' or 'belgain'). Because of those references, it seems to me that there's no doubt that these verses have their source in (or were adapted to fit) that 1984 Michael Jackson hair catching on fire incident.

Mind you, I'm not sure that children made up these verses. I think it's highly probable that some adult (for instance, a television comedian) made the verses up and children heard them (perhaps from other adults repeating them). I think that it's likely that children picked these verses up, added to them purposely and through folk etymology, and started passing them on by word of mouth to other kids.*

I think that is a likely scenario because these verses are so widespread that it seems to me that their dissemination needed to have had some assistance from the mass media.

*Of course, one way that these rhymes are being disseminated is through Internet sites such as Mudcat and my website on children's rhymes, Cocojams.

There are other websites (such as the "In the 80s children's rhymes" site) that have a few examples of these verses. However, most websites on children's rhymes only have a few examples of the mildly competitive, non-insulting versions of "Hanky Panky" hand clap rhymes.

If you're interested in reading a lot of versions of the insulting versions of this rhyme, the best Internet resource is
Origins: Down By The Banks Of The Hanky Panky