You can make Duplo blocks. I printed some nice adapters that let you build a bridge for wooden Brio railroad tracks, with Duplo stands. And it think you could make specialty parts, like it excavator arms. But for regular Lego pieces, printing is too expensive and not accurate enough (don't know about resin, but I can imagine it is not flexible enough or too toxic?).

What's really holding us back is copyright. I wish there were high quality Ninjago or especially Star Wars clones.