I wouldn’t call it a “problem” or “unwatchable”. It just will look like you are watching a game streamed online rather than one directly from an antenna, which is still quite good. There isn’t anything to fix, as that is the nature of 1080i data being transcoded to 1080p at 30fps.
You just need to weigh your options. If all you want to do is watch TV on television sets (and not on your computer, phone, or tablet), there are options out there that are a truer replacement to the cable/satellite DVR. But if you want the flexibility of watching TV on any device, including outside the home, then I don’t think there is anything better than the Tablo. Transcoding the data immediately provides that flexibility, with the same costs as other transcoded apps (WatchESPN, anything live on Sling and other streaming providers, etc).