echo - backslash interpretation

When looking at echo's manual page, I see -E is used by default:
-n do not output the trailing newline
-e enable interpretation of backslash escapes[/HTML]
-E disable interpretation of backslash escapes (default)

But why -E needs to be added anyway to disable this interpretation ?

Code:

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$ echo "Hello \t \World"
Hello    \World

$ echo -E "Hello \t \World"
Hello \t \World

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Shouldn't it be used by default ?

It is used by default, but lets say you decide to change it to enabled -e, it then stays that way (not set at default) until you actually change it back, so yes, -E is also 'needed'....