The following is based on 55 years of management training and experience working for one of the largest corporations in America and several smaller companies in corporate America in positions that range from 1st level to "C" level, employee training classes on this subject conducted by HR Depts. in those companies.
This is my advice.
Hourly or Salary
Hourly: If you are hired to work a 40 hour week and your company establishes a 9 -5 or an 8-5, that's what they expect from you and when you accept to work for them, that what you agree to. If you do not take the lunch break you can be directed to do so. If you choose not to, you are in defiance of a company directive and subject to discipline and possibly termination. You are breaking your contract.
Salary: If the company wants you to work as an exempt (i.e. exempt from over-time pay), you may choose to take the job or not. Your decision.
If the job requires acceptance of variable schedules, fluctuating hours, or certain additional or higher level responsibilities and risk management, it may well be deemed a "salaried" job. Generally, salaried jobs have more flexibility but require more commitment from the employee. Fixed income is a benefit to some and is considered to even out the time worked over a year. Example: Recreational activity may require a Dock Manager to work 50 - 60 hours a week in the summer but be offset by "Weather Days" that may be days off in the winter.
Salaried folks are either committed to the job and work as many hours as required or they prefer the Salary as a form of guaranteed fixed pay and know they are required to work more than 40 hours.
If an employee requests a conversion from hourly to salary, it could be to gain a benefit of working fewer hours by having more hours (or days) off from work, effectively earning more and working less.
The management issue is to determine if the job meets the litmus test of value (work vs. pay), risk management, client service, and necessary availability or it should remain an hourly job and be managed to obtain the results and the work hours agreed to. If the job does not require the use of judgment or work under variable hours and conditions, or if the employee is not required to work a minimum of 40 hours, (perhaps as much as 50 - 60 hours some weeks) then it should be hourly.
If the Job Description for the position defines duties that require work of more than 40 hours of work, it should be defined as salaried and the employee can accept or refuse the job.
My last opinion point is this: In either case, the manager is responsible to the company to get a fair day's work for a fair day's pay. Whether calculated on a daily, weekly, monthly or annual basis. The employee's responsibility is to deliver what has been agreed to. In a salaried position it is more of a deliverable, such as a service, a project, an objective, or a goal. In an hourly position, it is the work and the time as projected.