The problem with "loser pays" in this country is that everyone is guaranteed the right to judicial access. Loser pays presents a variety of issues in that regard, and for a few reasons I'm too lazy to discuss right now will likely never become law absent an amendment to the First Amendment depriving you of your right to petition for redress.
With that in mind, a more practical solution in my opinion is to require complaints - the documents initiating a lawsuit - to contain actual evidence. As in, if you don't have actual evidence supporting your claim, you don't get to file it.
Under the system as it exists now, you file your claim and then develop, through a potentially lengthy and always expensive process, the evidence to support it. Of course, there's no burden on defendants to disclose any potentially damaging evidence before a suit is filed, meaning that you often don't have a choice but to file suit. Meaning that a part of this system would impose an absolute obligation upon any potential defendants to disclose any relevant evidence upon receipt of some kind of notice from the potential plaintiff.
That would prevent a whole lot of cases from ever even reaching a court. They'd either be settled before filing, or never filed for lack of any evidence.
In Texas, some types of suits (med mal and claims against architects/engineers) require a Certificate of Merit, prepared by a competent and licensed practitioner of the profession about which complaint is being made, accompany the Plaintiff's Original Petition (Complaint). There may be other types as well.
It creates an interesting tension, because a professional who whores-out Certificates without appropriate inquiry and basis could be liable to the professional licensing authority for their profession, could lose their license to practice!
I can speak principally about the architect / engineer one, as I encounter that in my practice frequently. A suit filed without a required Certificate of Merit can be dismissed, with prejudice, by the Court!