@RVgeeks It is Realmac Software who are in charge of the theme API. Theme developers can only work within the limits of the API provided. So if for example you want to see the ability to open the page inspector or site settings and change what heading level is applied to the site title via a drop down select, then this can only be implemented by Realmac, at a RapidWeaver level.
Currently the theme API only allows for dropped banners, logo images, style and colour changes. There is currently no mechanism that exists for heading levels to be toggled or to write other HTML modifications into the page template. Regrettably, theme developers do not have that level of control. Of course, I would love to see the API expanded to include such features. But sadly the rate of progress is slow, compared to other APIs (like Stacks).
I suggest that if this is something you want to see, then you speak with Realmac Software about it. If they think your idea is credible and something they are willing to build into RW8 or whatever, then I'm certain many theme developers will work to incorporate it too. Theme developers want to make their products as flexible as possible, but avoid users from needing to meddle too much with custom code or other complexities. For that reason, the site title is normally 'locked' within H1 tags and not editable by the average user.
To be honest, I've not seen any hard proof that wrapping site titles in H1 tags is bad for SEO. It's not something I've encountered on any of the websites I manage for clients. This has been a standard practice in many themes for over 10 years and not unique to RapidWeaver. Any credible information you can share that proves otherwise would be of interest to myself and others.