Literaly the answer is NO and YES but carefully and only with good justification.
Oviously modifications or cleanup to the windows registry haves Advantages and Disadvantages.
Im personally against that Registry Cleanup Software which made a one touch registry clean task, without any noticeable warning, you always should keep in mind the scenario where it is mandatory to touch the registry.
Some viruses and malware, stores registry keys to reinforce the infection. you should use some anti malware software feature to remove that malicious keys from you registry and in that scenario the Registry modifications are justified.
Registry Damage/Registry Corruption:
If you experience Registry Corruption or Registry Damage you could use an especific tool to recover your lost registry keys from a previous backup.
There are only 2 scenarios only as example, but could be many more.
And be carefull using Registry Tweakers only because you was warned by an ad or by a mail or for amateur forum, it could be only a trick to infect your system, there are some Scareware just to made some scamm to good people.
Only using Registry Cleaner to remove unused keys or orphan registry keys maybe will Boost the Start-up cause registry will be smaller and will take less time to be loaded.