Opening/closing multiple file could definitely be made to work better.
In version 1, the quickpanel matching algorithm wasn't 'fuzzy' and you could prefix the search terms with '-' to denote exclusion operation.
If you pressed ctrl+enter it would open 'all at once' the matching files.
What kuroir is proposing, a sequential opening of files, could be quite handy also, and would work with the fuzzy matching.
As for dealing with multiple files simultaneously, maybe another less fuzzy matching mode combining globbing/regex with exclusion capability could be created.