I am indeed fully aware, and accepting of, the fact that in the early stage of Socialism, it will necessarily have many features of Capitalism, including the existance of commodity production and markets.
I apologize if I failed to make my argument clear, but commodity production and markets can not exist if Socialism is to advance into Communism. Deng's entire "Socialism with Chinese Characteristics" ideology fails to understand this. Commodity production, or in other words, economic goods that are given in exchange for money, must be slowly phased out of the economy as Socialism develops. In Stalin's USSR, this was already occurring - more-and-more goods were being given to the people in a way that was not a commodity. Given a few more decades, commodity production could have ended totally in the USSR. Unfortunately, Stalin's government, and therefore his economic policies, were couped and removed by a revisionist clique of Khrushchev.
As to the role of markets, they inherently create, as Marx put it, "commodity fetishism". Markets themselves are totally related to commodites, and therefore are capitalistic in nature. Markets are a network of non-state owned (under Socialism, this means that the proletarians to do not control a market) economic institutions which are present to sell commodites. Markets are furthermore capitalistic in the way that the people who run a market are almost always of petite-bourgeois if not bourgeois-proper class.
Because markets create exploitive capitalistic social and economic relations, they are therefore something which must be slowly removed from a Proletarian dictatorship, if Communism is to form.
Lastly, about your claim that:
"This was the same position of Lenin when adopting the NEP to the conditions of the Russian Empire and the peasant economy. And it was the position of Deng Xiaoping when adopting the Reform and Opening Up."
This is completly false. The NEP existed for the sake of developing the productive forces in order to turn the present state-capitalist economy into a socialist one, while still maintaining a Socialist state in the process. Their was nothing Socialist about the "People's" Republic of China, not even under Mao Zedong. The "Communist" Party of China, during the days of Mao, was a social-fascist revistionist party, which was perfectly willing to share power with the petite-bourgeoisie in their nation. Mao Zedong himself was a careerist and Han-Chinese Ultranationalist, who cared little about the Proletarian revolution, and only about the betterment of China.
In the wise words of Enver Hoxha:
"Chinese propaganda presents it as a revolution launched spontaneously from below, by the masses. But in reality it had to be organized. By whom? Here the figure of Lin Piao emerges. But how is it possible for such a Cultural Revolution to be launched by one person; while the Party and its Central Committee remain in the background? Only the Central Committee of the Party can take such decisions. It is a fact since 1956, when the 8th Congress of the CPC was held, more than five years have elapsed since the time when the 9th. Congress should have been convened. Why is this?
Normally, also, Plenums of the Central Committee of a Marxist-Leninist Party are held twice a year; but the recent Plenum of the CC of the CPC was held after four years delay! Then who is leading the Party? I suspect that since 1956, Mao has been left on the sidelines and turned into a mere symbol. Recently the Party has been completely over-shadowed by the name of, Mao Tse-tung. Behind the fanaticisation around the person of Mao Tse-tung lies something very dangerous."
The Chinese Revolution was doomed from the start, it was always capitalist and revisionist in nature. Deng simply persisted in Mao's revisionism, and sold out his people to Western corporations, and today, the PRC is one of the most unequal countries on this planet.