Yes, MVC development requires widget development to be completed fully and not provided by Kentico. Unless you utilise the widgets from Dancing Goat website.
Portal Engine did provide easier options to create widgets, but I feel this is because it was around for a long time. I feel MVC will also be like this over time. We all would need to adjust and adapt towards it.
I feel MVC allows the options to be flexible enough for people to create their own widgets/components to their own requirements. It also gives you the ability to standardise your development as a company, so there are benefits to this. Depending on the skill set within your company, you can create the widgets functionality in a front end technology that suits you e.g. VueJs or ReactJS or jQuery etc...
There are a lot of benefits going forward using this approach.