My bank's mobile app is 200 MB. The website is 10 MB, but most of that is wasted — it could realistically be built in less than a 1 MB. Start-up times and performance are similar.
Why should I lose/waste 200 MB for something that i have to be online to use anyway?
On the other hand, I also believe that this 200 MB comes mainly from 2 sources: bad engineering from the application developer, and bad engineering from the platform developer. These are not toolkit dependent, however. Bad engineering will create bad products, regardless of the tools used, even when some tools are harder to misuse to create bad products.