It is merely optional in both meanings. In other words, it is not required in either meaning. Just like it is optional in 好玩 ("fun").(1) 子女 (a son or daughter; an offspring): 是誰家的小孩考上了研究所?
(2) 幼童 (a minor, particularly one between birth and puberty): 你還是個小孩兒, 不能喝酒.
Although it is optional, I think I am more inclined to add an 兒 for Definition #2.
What about just 玩 ("to have a good time")? Is 儿化 necessary or optional?For 好玩, 一点, the 'er' is kind of optional. Without 儿化, people can still understand these words. It's just a matter of dialectal difference.
For most northern Chinese who are used to "er", they'll make the sound in speeches anyway, regardless whether it is written out in text.What about just 玩 ("to have a good time")? Is 儿化 necessary or optional?
I think it is optional because Collins give the following sample sentence:
That's right. It is mentioned in post #10. 儿化 is generally optional. It depends on the dialectical habits.I seem to remember reading somewhere (though I can't remember where) that there are only two words in 普通话 where 儿化 is compulsory: 一会儿 and 一块儿. Aside from these two, it is always optional.
It seems we have different understanding about the word "play". In Chinese, "玩 (play)" can be the verb for any ACTION you enjoy in your leisure time, such as watching TV, partying, shopping, travelling. You "have a good time" BECAUSE you "玩 (play)".That's not the impression I got. Whenever my Chinese friends tell me that they visited such and such city, I ask them "为什么？" and they invariably reply, "玩" (or "玩儿"). I assumed that they meant "To have a good time."