Which would be worse in a training- the lack of good content or the lack of "Why" the recipients are receiving the training?

1 - training content not related to work 2 - training content is only theoretical and therefore fails in the development of practical skills of the employee 3 - training material be bad 4 - trainees have no interest in training 5 - the coach is unable to deliver information or skills development

Let me answer this question but from different perspectives Maybe you're choosing the wrong person ! Unskilled labor and sometimes you can choose the right candidate but there's no customization based on title and job description or you just treating the training department as the know how and you have the concept they have the tools and equipments and from their current job they will learn by doing or another assumption but the truth is if the candidate didn't start by knowing why we existed, what's the vision,mission of our company and the values he or she will apply on daily basis, added to understand how the roles and responsibilities and the system they will work on each and everyday and the target expected in terms of numbers ...etc will not be able to succeed.
My own formula for training : as mentioned before people or job seekers are asset added to know how added to activities based on the roles and responsibilities = income which is your productivity

I believe both should go in parallel, as the training should be targeted based on the trainees' needs and they should be aware of why they are given this training,the outline and outcome so they get into the training with certain expectations.
Then the content,trainer and delivery method will determine if the expected learning points/ outcomes were met.
I believe a better way to assess the training is by not only providing the outline but also top 5 learning lessons and then ask participants if they truly learned something.
Also the trainings should be tailored and addressed to the right audience to ensure maximum benefit (Quality not quantity), and we as training dept.
should assess the training materials and the delivery method with the trainer prior to the training.

1 - training content not related to work2 - training content is only theoretical and therefore fails in the development of practical skills of the employee3 - training material be bad4 - trainees have no interest in training5 - the coach is unable to deliver information or skills development

I would say both WHY and HOW is important but WHY has more weightage.

Content is valuable, why is not so, sometimes refresher training is important to refresh important parts of job skills. for example, pilots have refresher training. They don't question why, because they are aware of the importance

 Not the lack of good content but the lack of the applicability of the content of the training.

As we all know the training cycle consist of 4 steps.
1.
Training Need Analysis i prefer to use the term (Learning Need Analysis).
2.
Design.
3.
Deliver.
4.
Evaluate.
The WHY falls in the first step which is the learning Needs Analysis that determines the areas of improvement and why we need to conduct this training.
The second step is the design step and now a days they say it much bette if you involve the participants in design the program and the content anf of course the facilitator knowledge and his skills plays a big role in achieving the training goals.

Training and learning are mutual concept.  If the objective of the Training is well defined, a good trainer will certainly make it simple to understand the concepts in spite of difficult or technical jargon type materials.  Basically training is simplifying the concept for the learners. As being in the professional services, every individual is trained to extract the needed skills to perform the desired functions in training. I believe both should go in parallel, as the training should be targeted based on the trainees' needs and they should be aware of why they are given this training, the outline and outcome. Then the content, trainer and delivery method will determine if the expected learning results were met.  

People in a training room know the reason why they are in the training room in the first place..Lack of good content is the worst senario...

Lack of why the recipients receiving the training is worse. The need for training should be specified first in any training and development program in order to identify the right content. At times content of program can be altered to align with the newly identified need of a training program