not really an option since it will mess up the code in other places where the block is used.
what i'm seeing though is this; if i insert a plain text (general) block on a line by itself, then view the source (with TinyMCE Advanced installed), the opening/closing 'p' tags are present. however when previewing/updating the page and then checking the source in the browser, they are both gone.
and then, as previously mentioned, if i insert a block on the same line as existing text, the opening 'p' is AWOL when previewing. sometimes the source ends up in the browser source as...
block hello world<p></p>
sometimes just the closing tag is there.
so i'm not really sure what is responsible for stripping the tags.
what do you think?
if i add anything before and after the block - even just a dot - then the tags are not stripped. so, apparently, TinyMCE and/or WP simply doesn't "see" the blocks and so it strips the tags - this explains why only the opening tag is stripped if the content block is the first object on a line with other text. CKEditor produces the same results (i just tried it).
could you try just putting a plain text block on its own line, as a paragraph, then save/preview the page and look at the source in your browser to see if the tags are there?