One of my least favorite aspects of all versions of Dungeons and Dragons have been the prevalence of vanilla “plus” weapons. They’re just boring. A long sword +1 feels an awful lot like a purely mechanical reward–less “magic” and more “accountant”.
It takes very little imagination to add a minor cantrip or bit of flavor to a magic weapon to make it exciting, but it provides a tremendous amount of interest versus the simple “plus” bonus.
This is not to say that magic weapons should not come with plus bonuses, but these plus bonuses should reflect the magic nature of the weapon, not define it. Take a look at my Waxing Sun/Daylight’s End dual sword for an example of what I mean, and here are a few more sample items to illustrate how minor mechanical effects can add a lot of variety to low-level magic rewards.