玩 / 玩儿

Hiya

I've noticed several times on the site, usually in expansion sentence or something, that where 玩 is written, it's always pronounced in the audio as 玩儿 "wár", rather than "wán". Is there a reason that 儿 is always missed off for 玩? 

For a recent example see the expansion sentence in the "what does she look like?" intermediate lesson:

►今天的天气不冷不热，出去玩正好。