Did it really take them so long to think about a symmetric port?
closed as primarily opinion-based by Andy aka, Michel Keijzers, Dave Tweed♦ Nov 9 '18 at 11:32
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Although @jsotola has a point (never underestimate the stupidity of users - they’re so creative!), the answer is more likely to be “complexity”.
USB was a proposed solution to a problem, and to succeed needed to be adopted as quickly and broadly as possible. To facilitate this, it above all needed to be cheap. This means that it needed simple circuitry, and as few proprietary chips as possible.
There are two sides to “symmetric” (pardon the pun):
- You can insert the connector either way around;
- Either side can provide or demand power.
The first adds complexity in wiring; the second adds complexity in power design. Both would have added to the cost, reducing the chances of widespread acceptance.
Now that USB has gained de facto ubiquity (even Apple have gone USB-C!) you can make these sort of user-experience modifications - and have no doubt whatsoever that they’re very complex and difficult! Getting it right has eluded many suppliers for a long time. Luckily, a number of chip manufacturers have solutions to help, so they’re not as expensive as they would have been at the beginning.