I think you are not completly understanding what is happening here.
If setting allow_url_fopen turned off in php, then you wont be able use remote files in include and some other php functions.
even if you find a way to avoid such restriction without .htaccess, it would require updating any files that currently include remote files with the changes. So I dont see why what I suggested above would not work.
In fact, if you include (execute) a remote file, you are not in control on what kind of code in the file, so your server become vurnable. Even if its a trusted host, they could get hacked by someone and your server could get compromized as well.