using bash features in init scripts

Is there any reason not to use bash features in init
scripts?
Consider, for example, this fragment from
/etc/sysconfig/network-scripts/ifup-post:

    DEVICETYPE=`echo $DEVICE | sed "s/[0-9]*$//"`
    REALDEVICE=`echo $DEVICE | sed 's/:.*//g'`
    if echo $DEVICE | grep -q ':' ; then
        ISALIAS=yes
    else
        ISALIAS=no
    fi

In bash we can do this much faster with something like
this:

    DEVICETYPE=$DEVICE
    while [[ $DEVICETYPE == *[0-9] ]]; do
        DEVICETYPE=${DEVICETYPE%[0-9]}
    done
    REALDEVICE=${DEVICE%%:*}
    if [[ $DEVICE == *:* ]]; then
        ISALIAS=yes
    else
        ISALIAS=no
    fi

Okay, the loop that replaces the first line is messy,
but it saves
a couple of forks and an exec.  The other two changes
are both
simpler and faster.

So why do most init scripts use sed and grep to
process
strings?  It can't be a desire to allow them to work
with the
Bourne shell (why would we want that anyway?) because
some
scripts do use bash features.

[email protected]


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