I personally am not forcing you to use C++. I presume that if you work for a company for example that they may take an interest in what language you use.
But strictly speaking, efficiency is one reason to use C++ - if you don't care about it, that's another matter. Providing functions that promote efficient use of the underlaying data structures make sense, however.
Yes, modern hardware has lots of memory and lots of clockcycles per second (at least in a PC), which allows the use of "slower" coding practices when that's suitable. Fine - that doesn't mean that C++ should be changed to be slow always, does it?
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Mats