Kids should start on HTML. This teaches simple coding (UI elements only) so it is great to for them to see quick results of their efforts.
Most beginner Hypercard apps were just multimedia pages hyperlinked together. You can do that now GitHub right now and publish it immediately to a web site. It was fast and easy to get my 10-year-old daughter a GitHub account and show her how to use the online editor. Then I showed her HTML and CSS and let her loose. I set up github pages and gave her instructions to pull to that branch (which took me a while to figure out but she took right to it.) She took my netbook into school the next day and blew away the kids in her project group with it. Then she got bored and hasn't wanted to mess around with it anymore. Oh well...
As an interested parent (although of a 4 yr old), did she get bored because she hit a wall in what she wanted to do? With HTML its fairly easy to generate a nonlinear text and image based story, but I imagine trying to add any sort of interactivity through the mess of CSS and JavaScript might quickly lead to frustration. Unlike HyperCard, today's technologies don't seem to have a smooth learning curve as you try and build more complex things.
No she just got bored because that's her. HTML can have a smooth learning curve but its not baked-in so you need someone to manually guide them and since most adults don't know how to do this that's a problem. My point is it is solvable, not inherent.
Most beginner Hypercard apps were just multimedia pages hyperlinked together. You can do that now GitHub right now and publish it immediately to a web site. It was fast and easy to get my 10-year-old daughter a GitHub account and show her how to use the online editor. Then I showed her HTML and CSS and let her loose. I set up github pages and gave her instructions to pull to that branch (which took me a while to figure out but she took right to it.) She took my netbook into school the next day and blew away the kids in her project group with it. Then she got bored and hasn't wanted to mess around with it anymore. Oh well...