Did you read it or just skip to the parts you liked? Your question was why they didn’t leave the USSR.

From p. 78 of the first source:

While there is some sentiment in favour of secession from the Soviet Union, this does not reflect majority opinion. There is little or no evidence of any significant inclination to replace socialism with capitalism, despite significant dissent about the particular forms of Soviet institutions existent today. The benefits to Estonia of being part of the Soviet Union have proved to be immense.

I’ll let others comment on the elections.