I had the same gripe about Opera when trying it out. There's two solutions
Enable shortcuts in Advanced settings. The default tab cycle hotkey is 1 (back) and 2 (forward). The flaw in this is that the webpage may also be using number input i.e filling forms, youtube.
You can customise a hotkey! This is what I did and there is a tiny learning curve but it's probably well worth it for a great browser! (I'm still new to it).