The lack of clear evidence for manipulation in Estonia is not a strong argument to introduce it in a more high-value target. Switzerland has been "trialing" e-voting for decades with very limited success.
The societal context is different. In Estonia, everyone uses the id-card for everything and has for 10+ years. Everyone understands, that handing your card and pin-codes over has severe consequences. Also, the e-voting does not function in isolation. If a person has voted electronically, whatever paper vote they cast will override their electronic vote.