Magento extensions can always be improved and as a developer you need to know many things before you should submit extensions to the Magento Marketplace. Using static code analysis tools like PHP CodeSniffer allows for improving code quality, without that much effort. However, the rules are lacking. This is partially due to growing insights, evolving code, but also because there aren't enough rules yet. Magento has worked in the past on the ECG and ECG2 rulesets, the Magento Marketplace team works on MEQP2 (Magento Extension Quality Program), ExtDN has its own ruleset and there are many more rulesets that could be incorporated (Symfony ones, Object Callisthenics, possible PHP7 checkers, etc).
This table is meant to kickstart a talk on how we can contribute to create more rules, validate and document existing rules and also work together to develop more analysis tools besides PHPCS. A real developer topic with a focus on in-depth PHP/Magento annoyances!