Right!? Even the best friend duos that are often played as childish, they are often way more supportive and loyal than their romantic partners are. What I liked most about the fic I read was that both MCs spouses were completely supportive of their friendship. The famous actor and his wife became the aunt and uncle to the female MC's kids. The big kick in the butt for her to accept the her bff's proposal was her kids telling her that they've loved and supported each other all the kids' lives, so why not do it as an official couple?
Even if they don't get together romantically, I think households where a bunch of best friends commit to raising children together (Full House) is much better than a child being raised without a loving family.