I'm not sure it was the case in 17h century. Russia was just too far. Even during Peter the Great's Prut's misadventure Balkan Slavs didn't believe in Russian ability.
1640? Dubious. Remember that during this time Russian court refused to accept already conquered Azov fortress from Cossacks, as they considered it being too far and not worthy of effort. Russia was just reeling from Times of Troubles, couldn't do much against PLC during so-called "Smolensk War" and Romanovs were a new dynasty with rather dubious legitimacy. Taking on Ottomans at this point was just too much.
Could you spare us rather dubious propaganda speeches from Turkish schoolbooks, please? Believe me, Ottomans amassed an amazing amount of bad blood in course of their Balkan adventure, and even bigger amount of anti-Ottoman propaganda had been created. You don't see much of it being posted here, don't you?
Turkish schoolbooks are very negative about the Ottoman Empire, so spare me your assumptions. The "bad blood" regarding the Ottoman Balkans was amassed
after independence in nationalist historiography, not before. What I'm interested in is what was actually the case, not what 150 years of national indoctrination (on both sides) has inculcated.
Russia didn't even liberate it's
serfs until 30 years after the Ottomans gave Christians legal (if not effective) equality. There is no comparison between the political liberties and economic level of the Ottoman Balkans in the 19th c and Russia - a fact not lost on a lot of European observers. The difference was that Russia was militarily strong and so it's flaws were glossed over due to balance of power concerns. The Ottomans were militarily weak, so it was convenient to exploit the imaginary "Turkish Yoke" for geopolitical purposes. Not that Ottoman rule was ideal, but nobody seems to have managed to do better.
When Russia was edging toward unprovoked war in 1877, the sectarian communities of the empire were unanimous (with the exception of the Protestants) in petitioning the Tsar to lay off. All preferred to pursue their national development within the context of the Ottoman Empire than within the Russian. And why shouldn't they? The Ottoman Empire was free-trade and they had religious autonomy. For all the flaws of the late empire, that was more than they were going to get from Russia.