... if you really wanna go toe-to-toe with the big guy (ETH), the ease of use should be comparable. People these days hate desktop wallets for some reason and the NXT one isn't really the most casual friendly or good looking one. On the other hand, nobody in their right mind runs an Ethereum full node at home either. This is why MEW is the de facto official ETH wallet. If Ardor/Jelurida offered a web wallet like MEW or a highly polished desktop wallet I believe this would help immensely.
Some of your points are already addressed, others are in the roadmap as far as I know.
Anyone can use now
https://nxt.jelurida.com as public Nxt wallet without downloading anything. They also have testnet public wallets for Nxt and Ardor, and will make available an Ardor mainnet public wallet after launch.
Also, the Nxt Client can be installed in light mode and no blockchain download will happen. The client will use API and blockchain data from remote public nodes.
But it is true that Nxt/Ardor could use a simplified version of the desktop wallet. I think Nxt has a great wallet, but I'm used to it and I understand newcomers can be overwhelmed by a lot of tools that could be under the "advanced" hood of a simplified wallet.