As you may or may not know, I spent the first third of my career so far in production. In that time I learned a lot about producing oil and gas wells, and one thing I learned is that downhole packers (between casing and tubing) really have a way of limiting your production options. The reason is that it cuts off your access to the annulus, thereby leaving your only downhole access through the tubing, which is where your reservoir fluids are being produced up. When a well has a packer, there is no easy way to provide continuous chemical injection into the well. This means that soap, corrosion inhibitor, salt inhibitor, and a whole slew of other valuable production chemicals cannot be easily injected into the well without shutting in the well. This leads to expensive capillary strings and/or other non-desirable options. For this reason, I don't like packers and I recommend trying to avoid them.
With that said, packers do serve a purpose and sometimes they are necessary. In these situations you will obviously have to install them and deal with the consequences. However, I've seen far too many times where a packer is installed as a part of the completion process, with no regard to the production impacts. I think this is silly. Production is the only point where you make money on a well, and therefore great consideration should be taken when making drilling or completion decisions that will negatively impact production. My advice is to use packers where absolutely necessary, but nothing more.
For those of you in drilling or completions, this may sound silly. Just trust me on this. Your production folks will appreciate it.