I don't think it's limited to those two apps. I use neither of them and I still have issues. Perhaps Whatsapp and hangouts add similar callback hell to the widget?
Because, at Google you do not get promoted if you make small incremental improvements. Especially not if you work on something that does not easily show up in metrics.
You need to launch flashy products and APIs to have the promo committee look at your packet properly. Unsurprisingly, promo driven development ensues.
Google isn't the only stakeholder here. Users and app developers could contribute improvements through AOSP.
Whether or not they'd see the light of day is another question, but it's surprising that stupid issues like this aren't tackled more by the people suffering.
