You absolutely can and you must. Being professional and being nice are not exclusive. Quite the opposite.
A professional manager understands that being nice doesn't mean protecting someone from reality just because reality sucks. It means showing them respect during the process.
The lesser and lesser rights of employees is a power grab. Employees still needs to pay high rents, expensive mortgages, bring up kids and everything else. If anything that has become harder to do successfully by working.
I really don't think a lot of companies are going to come out favorably in hindsight if there is a downturn.
Is it 'unprofessional' to deceive your employees and customers or users? Is abusing the privacy of your users professional? Is it unprofessional to layoff workers for short term gains? Its definition itself is contextual to power and what it defines at that time. Individual bad behavior is not unprofessional, its just bad behavior.
Hold paramount the safety, health, and welfare of the public.
Perform services only in areas of their competence.
Issue public statements only in an objective and truthful manner.
Act for each employer or client as faithful agents or trustees.
Avoid deceptive acts.
Conduct themselves honorably, responsibly, ethically, and lawfully so as to enhance the honor, reputation, and usefulness of the profession.
Maybe we need a code of ethics for managers.
Entire forecast change when numbers are missed. People are also hired based off those numbers. Should we also not hire more employees when the out look is better?
Companies need to be healthy to continue to be able to employ at all. So yes. It is the duty to cut cost and maintain healthy balances based off future expectations.
It would be far more dishonest to simply let the entire company fold effectively laying off everybody to prolong a subet of employees jobs for a little longer.
But beyond that it's rare that layoffs happen for a single quarter miss. And unless you are pure EBITA driven laying off probably won't make anybody looking for revenue groth happy either.
Companies are complex living organizations. The notion that laying people off is always bad is a bad notion.
Economic cycles are not a surprise, they happen, a company with enough resources can easily absorb them, use the down turn to double down on developing new products, and come out stronger on the other end.
Laying people off isn't always bad, but at least 80% of the time it's the wrong long term decision. You've spent years on these people learning your products and technology, and now all that knowledge is gone. The impact is continuously felt years down the road. The movement of people this and a variety of other reasons is a net drag on companies. This treatment of people as some sort of "resource" that can be scaled up and down on demand is a joke.
All that is not to say that if you have a problem with specific employees you can't fire them, that's a completely different question.
EDIT: Lemme give you another example I witnessed personally from a multi-billion dollar company. Production of a certain (highly complex) product in was moved to Mexico for a projected cost saving of about 5%. The factory was closed, hundreds of people were laid off. Years later the production cost in Mexico was higher than the cost in the original factory and production was moved back. It was absolutely clear the original decision was iffy but it was done for the optics of making it look like the company is working on cutting costs. It impacted not only those people who got laid off but local supply chains etc. Overall a negative decision for the company, the economy, and the people involved, driven purely by bean counters with no clue. If the company did "focus on employees" and really considered the loss of know-how, the cost of recruiting and training people, the loss of trust, the impact on morale etc. maybe we would have had a different outcome.
If your boss needs to take into account the personal consequences on the employees they fire, then now employees have to start playing a bullshit game of convincing colleagues how precarious their personal situation is and how much stress and uncertainty is in their life and how their family depends on them. The stoic professionals who just get things done at work are effectively getting punished for focusing on delivering value to the business.
Like, I get it, professionalism definitely has downsides. It also has advantages. People know how things are going to work and can focus on things that are more relevant to the core business. It's a trade-off.