Improving on things isn’t a waste of money especially if they’re successful enough to achieve the main goal, ie. make games more accessible to more devices, instead of making the perfect handheld (which is unlikely for a first iteration). The body is too big for the screen, too heavy, new SOC means new considerations internally like cooling and battery, keeping the current form is arguably more stupid since it will probably limit actual improvements.
Most people will need internet connection to Google specific commands to run or install the most trivial things, and it won't always work depending on what distro you're using. Oh you're using MX Linux? Goodluck downloading a Plex client installer and just clicking it to install. Maybe use Snap but then good luck creating a shortcut with just a right click.
Limux won't replace Windows anytime soon, not if even enthusiasts need to Google almost everything.