Why should countries allow foreign influence - the voting in the most important elections in the country, by foreign citizens who didn't integrate enough to even get their citizenship?
Participating in local elections is often allowed.
In the case of these two countries dual citizenship is not allowed. So for the rest of my life I will not be able to vote here. This isn’t about “not integrating enough”.
If someone has been living and working in a country for a long time that should be enough to let them vote in national elections, regardless of what citizenship they have.
Not willing to change your citizenship is a sign of not integrating fully, in not being completely loyal to the country and to its citizens.
Imagine that both countries start a war between each other - who are you going to support? Whoever you choose does not matter, the fact remains that you would have to choose, legally speaking. Why should your current living country give the strongest possible leverage to an untegrated potential agent/supporter of the foreign country?
Highest privileges should be given to people who decided to be fully in, in both good and bad. You can't be allowed to only cherrypick the good stuff: "I want to vote, but I don't want to be drafted to be killed in a war".
Participating in local elections is often allowed.