but letting Russians speak Russian
No one is forbidding them to do that - Russian speakers can and do provide service to other Russian speakers in a language they prefer - no one is punished for that.
In some shops employees have little flags on their uniforms that indicate their language skills - find one who has Russian flag and you will get service in Russian without any problem.
But Latvians should not be required to do that - if they do - that is a nice bonus, but Russians should not demand that.
If you think that Russian working in some government institution or customer service should only speak to me in Russian - then NO - they should speak to me in Latvian or get fired.

Speaking Latvian in Latvia IS NOT A DISCRIMINATION.
Just like speakin Russian in Russia is not a discrimination.

Maybe in the future...
When Russian tanks will come in?
It was not like they occupied you and started exploiting the country, like say, the Nazis did.
They did exactly that - and they invaded BEFORE Nazis came in - in 1940 when they and Nazis were ALLIES - USSR propaganda tries to not mention that.

but from the point of view of the USSR, they were genuinely liberating you and annexed the Baltics in a legal way.
But USSR does not exist now.
And from Latvian and most of Western world point of view they occupied us illegally.
Only cowards like Sweden admitted (at least for some time) that occupation was legal - USA and many other countries did not.
And it affected only a minority.
Almost everyone have at least one relative that was deported or otherwise persecuted by USSR.
Not to mention that these deported people and their descendants were later discriminated against even after Stalin's death.
But it does not matter how many people were deported - that was a crime against humanity - equal to Holocaust.
Pre-war Latvian government never did anything like that.
They built schools, libraries, hospitals, sports centres etc.
So did pre-war Latvian government - but they did not kill people.
And so does current government.
Before invasion - standard of living here was much higher than in USSR.
Other Latvians benefited from free education
Education was free in pre-war Latvia too.
And it is free now - I did not have to pay a single lat for my university degree.

The whole idea was that all the Soviet republics were equal
but Russia and Russian speakers were more equal than others.
Not only schools and hospitals were built in Soviet Latvia - factories as well
Factories which proved to not work in free market, because of shitty production quality.
And stuff RAF made was just terrible compared to anything that was manufactured in the West.

Btw xdns - thanks for correction