Is certain martial arts more suggested for certain sizes of people?

No. Martial arts are not suggested for people of certain sizes. Martial arts when taught correctly anyone of any size can use them effectively against a person of any size or strength. Martial arts were created use science. It is a lot of physics and anatomy. All humans share the same anatomy basically. Our joints bend only so far in so many directions. If you bend it to far it will break or tear something. Certain nerves respond to different types of pressure. Some need to be rubbed. Some need pressure and some can be struck. I won't go too far into that. But that should give you a basic idea. Therefore if we hit you in certain areas it is weaker than others. If we twist or compress certain areas we know it will produce a certain response. Armed with this knowledge gives us an advantage. We don't have to be bigger, faster, or stronger. We are just better informed and better prepared.

The style is not weak or stronger than any other. The person using it may not be as highly skilled. The person that taught it might not be as skilled. The problem is not the style. It is the individuals using it or teaching it. There are those that are good or decent at using what they have learned. This doesn't automatically mean they are great at teaching it.

You should always look for the best teaching and never choose based upon style. But you should decide if you want to learn a combat sport or a life preservation. That wold make a difference. If you want to compete a lot go to a school that focuses on competing. If you want to learn what to do if you are attacked on the streets go to a plca that focuses on teaching life preservation. Often people call this self defense. Then there are those that are very critical and will point out that self defense is a legal term. It is not martial arts. Also you have some schools that compete but also teaches good life preservation skills.

BJJ is basically a sport today. You do not learn how to defend yourself from attacks, weapons, or multiple attackers in most of those classes. They teach you have to defend yourself from things commonly done in a bjj tournament. You will learn some good take downs and how to control the person and set up your attacks to get a submission. Most of this competition takes place on the ground. This is not the best place to be if you are attacked on the street. While you are being patient working the progression in order to get the person to give you something their friend can easily sneak up on you and kick your head in or stab you. You are defenseless at that moment. Whereas a school that teaches what to do if attacked will teach you to get up quickly if you are on the ground and how to do it. The objective is for to send your attacker to the ground hard and wast and not for you to spend a few minutes n the ground. You need to end the threat quickly.

Jeet Kune Do is not a style. It was a philosophy. Bruce Lee stated that himself. Yet people capitalize of of his fame and make money. There are some schools that teach some great teach good techniques that are effective for defending yourself. But like every other school there are those that are not teaching so well.

Look for a good instructor. I can't stress this enough.

I don't think certain styles are more for certain sizes of people. I also don't think that Karate is weak. I met many Karateka who are really good and definitely are not ones to mess with. But I have found that sometimes the teacher is not good and then the best style can appear to be weak. Then there is also the incident where I had a teacher who was 250 pounds and strong as an ox. He was a good martial artist but surely had no clue how to teach a 110 pound person who was not as strong, so yeah it definitely felt that this was not down my alley at all until I figured out it was the teacher and not the style. So if you don't have a good Karate teacher in your area, by all means go with something else that fits you better. But be careful to jump to premature conclusions and judging a style.

No your way off base. Yes some are more suited for one body type than another. There are some inherent advantages and disadvantages to each body type. In reality size is no issue for a certain style or not.

As for Karate being weak. LOL your so wrong. Even some of the better MMA fighters have a traditional background. And this separates them from the pack. Karate will teach you things you will never get or understand from BJJ. Such as strikes and correct body and joint alignment which makes a strike even more powerful since you learn transition of power when striking.
As for JKD it is a concept which is more designed for someone with a martial arts background already.

Some techniques are not entire styles, styles are meant to adapt to your body type.

Kites are good for begining akido kids learn alot of kites with burning your hand.