There are actually some serious disadvantages to this from a privacy and security standpoint. Light clients are still very vulnerable to a malicious lightwalletd. You can see a rundown on these vulnerabilities here:
https://zcash.readthedocs.io/en/latest/rtd_pages/wallet_threat_model.html
Having lots of lightwalletd’s mitigates some of these issues, like the ability to analyze the transaction graph based on who is fetching memos, but as you add more lightwalletd’s, the chances of connecting to a malicious lightwalletd approach 1.