I would love to upgrade my multisite network to PHP 7, but rather than a matter of not understanding the benefits, it is a matter of supporting and/or replacing plugins and themes that are not PHP 7 compatible.

According to the PHP Compatibility Checker plugin, our multisite network still has 7 plugins and 5 themes that return errors with PHP 7, including one actively developed theme by Automattic (Edin) and one plugin by wordpressdotorg (WordPress Importer).

We have 22 plugins and 8 themes that have PHP 7 warnings.

The WordPress.org theme and plugin repositories should flag plugins and themes that are not compatible with PHP 7 and encourage the authors to update them. And it would help quite a bit if the major players led the way with PHP7-compatible plugins and themes.